The Anthracite Chapter NEWS - Weebly · The Anthracite Chapter NEWS September 2014 ASHRAE - Shaping Tomorrow’s Built Environment Today 2014-2015 OFFICERS & CHAIRS President: Matt

The Anthracite Chapter

NEWS September 2014

ASHRAE - Shaping Tomorrow’s Built Environment Today

2014-2015 OFFICERS & CHAIRS

President: Matt Archey, PE [email protected] (570) 821-1994 x257 President-Elect: Rich Karns [email protected] (570) 287-3161 x210 Vice-President: Patrick Salmon, LEED AP [email protected] (570) 586-4334 x3126 Treasurer: Alyssa Procida [email protected] (570) 654-0865 x234 Secretary & Membership Promotion Chair: Jon Keller [email protected] (570) 342-7778 Board of Governors: John Durdan, PE: (570) 586-4334 x3152 Dan Mello: (570) 288-8759 Board of Govs. & Student Activities Chair: Tracey Jumper [email protected] (570) 471-3480 Chapter Technology Transfer Chair: Dave Onufer [email protected] (570) 582-0814 Research Promotion Chair: Maxwell Tamasy [email protected] (724) 797-4908 Research Promotion Co-chair: Gary Debes [email protected] (215) 298-2922 Young Engineers in ASHRAE Chair: Will Seiberling [email protected] (570) 654-0865 Historian & Newsletter Editor: Walt Janus, PE [email protected] (570) 507-9015 Website Homepage Editor: Karl Grasso [email protected] (570) 562-2778 Grassroots Government Activities Chair: A.J. Speicher, PE [email protected] (570) 821-1994 x 303

President’s Message It’s hard to believe we already have two weeks of high school and college football behind us and the Wilkes University wrestling team has started its conditioning regimen, but these are both sure signs that fall is just around the corner. With that comes a new year of ASHRAE programs and activities, all of which are planned to build on the topics you requested to hear about over the past year. Last year was full of success for the Anthracite Chapter, and I would like to extend a sincere thank you to our officers, committee chairs, and all of the chapter members who contributed to that success. Your continued participation and support allowed us to provide multiple scholarships and educational opportunities at Wilkes University and Columbia-Montour AVTS and make a great contribution to ASHRAE research programs. All of your contributions truly are helping to shape the next generation of engineers and HVAC&R industry professionals. This year, Tom Phoenix, our new Society President, has declared his Presidential theme of “People, Passion, and Performance” as a way to encourage us to focus on the importance of developing and educating ourselves and our peers. Be passionate about all that you do, and that passion will become contagious, leading to great performance by you and those around you. In an effort to contribute to Tom’s theme and improve the future of the built environment, our Anthracite board has established goals for the coming year.

• Increase interaction between chapter members and Wilkes student members, working together on at least two K-12 STEM activities.

• Achieve a 10% increase in average meeting attendance, ultimately helping to educate that many more people so they can perform in this industry.

…continued on page 3

Chapter Website: http://anthracite.ashraechapters.org

ASHRAE ANTHRACITE CHAPTER MEETING

Tuesday September 16, 2014

Protected Premises Fire Alarm System Code and Standard

Requirements for HVAC System Interfaces

Presented by E.J. Kleintop

Mr. Kleintop is a two-decade veteran in fire alarm and suppression systems in the building industry, representing Tyco SimplexGrinnell with a diverse resume of technical and operational management assignments. Current responsibilities include product & business development, sales & engineering team support, and consulting technical resource for the specifying AEC and code enforcement communities. Active in industry relations, he is an NFPA 72 Technical Committee Principle representing Tyco Fire Protection and Building Products, as well as a Subject Matter Expert for NICET. E.J. holds a B.S. from the Pennsylvania State University with Honors,and a Specialized Trade Diploma from Northampton Community College in Electrical Construction. E.J. is a licensed and registered Master Electrician. He holds NICET level 4 Fire Alarm Systems Certification and NICET Special Hazards Suppression Certification. He has also been a certified Green Advantage Professional and a member of the International Code Council. He will discuss Protected Premises Fire Alarm System Code and Standard Requirements for HVAC System Interfaces. Material will be presented from a Mechanical Engineer’s perspective to include both NFPA and ICC references. Topics will include fire alarm and suppression system basic requirements, smoke detection options for AHU shutdown, smoke damper detection interface and control, proper fire alarm device location, options for challenging environments, other system interfaces, and smoke control systems. Both current and pending requirements for carbon monoxide detection systems will also be discussed.

A Certificate of Attendance will be available at the registration table

Meeting Details Location: Cooper’s Seafood House

304 Kennedy Boulevard, Pittston, PA (570) 654-6883 Schedule: 5:00-5:45 p.m. Business Meeting (All are Welcome) 5:30-6:30 p.m. Social Hour (in the bar, SPONSORED) 6:00-6:30 p.m. Program Registration 6:30-7:15 p.m. Dinner (Buffet) 7:15-8:30 p.m. Technical Presentation Cost: $ 30.00 per person FREE for Students (ASHRAE Members are encouraged to sponsor Students)

If You Are Planning to Attend Please Respond by NOON on MONDAY September 15, 2014 to Walt Janus at (570) 342-3700 Ext. 286 or via e-mail at [email protected]

NEWS and Notes President’s Message (Continued from Page 1)

• Establish our chapter as a technical resource to help educate those looking for guidance in HVAC and built environment decision-making by reaching out to local governing bodies.

• Provide continually improving learning opportunities for all members, regardless of experience We will continue to offer Professional Development Hours (PDHs) and certificates to our members for attending our monthly technical sessions. Our first meeting is focused on active membership, with our annual “Bring-a-Buddy” theme. I encourage you to bring a friend or colleague so that they, too, can benefit from all that ASHRAE has to offer. If you know somebody whose participation has been waning, please call and invite them to rekindle their involvement. The technical program you miss just might be the one with the greatest benefit to your next project. The success of the Anthracite Chapter and the HVAC&R industry depend on the dedication and contributions of our members. Control your own destiny. Please feel free to reach out to me or the other Chapter officers at any time if you have any suggestions or, better yet, are interested in volunteering. I look forward to serving you in my final year as Anthracite Chapter President and hope to see you at Cooper’s in Pittston on Tuesday! Thank you, Matt Archey

Past-Presidents Night

At our May meeting we recognized all past-presidents of the Chapter who were in attendance including (left to right) Dan Mello, John Durdan, A.J. Speicher, Lee Garing, Bob Mugford, Charlie Smith, Walt Janus and Dennis Gochoel.

More NEWS and Notes Technology Corner This month’s technical article, “Controlling Corrosion in Marine Refrigeration Systems” is attached at the end of the newsletter, and is courtesy of ASHRAE. Please submit articles for consideration to be included in future editions of the NEWS to CTTC Chair Dan Onufer. Sponsor the NEWS We are again offering the opportunity to sponsor our monthly newsletter. Sponsors will be recognized in each issue of the NEWS. The suggested donation is $50 for the entire year (10 issues). We are also offering to post employment opportunities for a donation of $25 for Chapter members and $50 for nonmembers per issue. Please contact newsletter editor Walt Janus for more information. Lehigh Valley Chapter Clay Shoot Our neighboring Chapter will be hosting a clay shoot on October 10th in Coplay, PA to benefit ASHRAE Research. Full details including a registration form begin on Page 8. Space is limited and registration closes on October 1. Call for Chapter Historical Items The Chapter archives are starting to fill up, but we still have more room available for any and all items related to the history of the Anthracite Chapter. Bring them to the next meeting or contact Dan Mello or Walt Janus to make arrangements to drop them off or have them picked up.

Thanks to Our Sponsors

The display of business cards in the NEWS recognizes the financial support of the Chapter by the individual or business and does not constitute an endorsement or recommendation by ASHRAE or the Anthracite Chapter.

Thanks to Our Sponsors

The display of business cards in the NEWS recognizes the financial support of the Chapter by the individual or business and does not constitute an endorsement or recommendation by ASHRAE or the Anthracite Chapter.

ANTHRACITE CHAPTER NEWS Walt Janus, Editor c/o Greenman-Pedersen, Inc. 50 Glenmaura National Blvd, Suite 102 Scranton, PA 18505

ASHRAE MISSION

• To advance the arts and sciences of heating, ventilating, air conditioning and

refrigerating to serve humanity and promote a sustainable world.

ASHRAE VISION

• ASHRAE will be the global leader, the foremost source of technical and educational

information, and the primary provider of opportunity for professional growth in the arts

and sciences of heating, ventilating, air conditioning and refrigerating.

2013-14 Matt Archey 2004-05 A.J. Lello 1995-96 Chuck Swinderman 1986-87 Jerry Peznowski 2012-13 Tracey Jumper 2003-04 Dennis Gochoel 1994-95 John Walker 1985-86 Lee Garing 2011-12 A.J. Speicher 2002-03 Phil Latinski 1993-94 Dennis McGraw 1984-85 Spence Martin 2010-11 Tom Swartwood 2001-02 Mike Moran 1992-93 Scott Harford 1983-84 Donald Brandt 2009-10 Brian Flynn 2000-01 Dennis Gochoel 1991-92 Dan Mello 1982-83 Rich Santee 2008-09 Eric Zanolini 1999-00 John Durdan 1990-91 Mark Hagen 1981-82 Bob Mugford 2007-08 Walt Janus 1998-99 Matthew Martin 1989-90 Paul Dreater 1980-81 Kerry Freeman 2006-07 John Havenstrite 1997-98 Dean Butler 1988-89 Bud Reilly 2005-06 Manish Patel 1996-97 Charlie Smith 1987-88 Ray Suhocki

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ANTHRACITE CHAPTER 2014-2015 MEETINGS & EVENTS

Date Theme Program Speaker

Sept. 16 Membership Protected Premises Fire Alarm System Code & Standard Requirements for HVAC Interfaces

E.J. Kleintop

Oct. 21 Bring-A-Buddy Plate Heat Exchangers in the HVAC Industry Tracey Putnam

Nov. 18 Students/YEA Technical Tour - Susquehanna Brewing Co. TBA

December Family Night -- --

Jan. 20 Research Promotion TBA TBA

Feb. 17 Membership : Joint Meeting w/PSPE : Engineer’s Week

TBA TBA

Mar. 17 Joint Meeting with

SMACNA TBA TBA

April 21 Students TBA TBA

April 23 ASHRAE Webinar TBA Panel

May Research Promotion Car Show --

May 19 Past-Presidents TBA TBA

June 16 Fun & Fellowship Mark A. Hagan, PE Memorial Golf Tournament --

Aug. 20-22 Chapters Regional Conf. 2015 Region III CRC --

*ASHRAE Distinguished Lecturer **ASHRAE Presidential Member

To: Fellow ASHRAE Supporter From: Frank Paretti President Date: August 4, 2014 Re: 2nd Annual ASHRAE Clay Shooting Event I am pleased to announce that we have scheduled our Second Annual Clay Shooting Event at the Lehigh Valley Shooting Club. This event should be a great opportunity for our members to enjoy time with other professionals outside of the traditional ASHRAE experience. As always, we thank all of our vendors and engineering firms for their past support of our annual ASHRAE Golf Outing. We are hopeful that we can expect the same level of support and participation for this unique event as well. Based upon feedback from our membership, we wanted to accommodate those of us who are interested in taking part in ASHRAE events but might not have interest in playing golf. Like the golf outing, the net proceeds from this event go to ASHRAE Research. This year’s event will be held at the Lehigh Valley Sporting Clays in Coplay, PA on Friday, October 10th, 2014. Lunch will be provided starting at noon and we will begin the event promptly at 1pm. If you are interested in this event, please fill out the attached forms and mail your completed forms and check to Frank Paretti (Address on Form). Space is limited for this event so please register as soon as you can. Please RSVP by October 1st, 2014 at noon. Please contact me at [email protected] or 610-704-2169 if you have any questions. Thank you from all your fellow Chapter Members!! Frank Paretti President - Elect ASHRAE – Lehigh Valley Chapter

2nd Annual LV ASHRAE SPORTING CLAY OUTING

Lehigh Valley ASHRAE

Please forward any questions to Frank Paretti – [email protected] 610-704-2169

Held at

Lehigh Valley Sporting Clays (LVSC)

Friday, October 10th

, 2014

FOURSOME PRICES - Lunch Included Cost

100 Targets w/ rental $480 This includes lunch, targets, firearm rental**, shells** and golf cart.

100 Targets w/o rental (Base cost) $360 This includes lunch, targets, and golf cart rental.

INDIVIDUAL PRICES - Lunch Included Cost

100 Targets w/ rental $130 This includes lunch, targets, firearm rental**, shells** and golf cart.

100 Targets w/o rental (Base cost) $90 This includes lunch, targets, and golf cart rental.

**Firearm rental (All rentals in one squad of 4 will share single firearm) and will

include ammunition (Rented firearms must purchase and use ammunition from LVSC and is

provided in cost)

Our guests may provide their own firearms and ammunition. “Bring your own firearm” is subject to LVSC policy.

Please call or reference the LVSC website with any questions about personal firearms.

Per LVSC policy, one experienced shooter must be in each squad. If you do not have this, you will be asked to book

lessons with their instructor ahead of the event.

Eye and Hearing protection must be worn per LVSC policy. See LVSC website for details (www.lvsclays.com)

A complete listing of course rules can be found at www.lvsclays.com

Due to the nature of this special event, no refunds will be offered for cancellations or changes to reservation.

Please complete forms and send with payment to Frank Paretti Lehigh Valley Engineering 1 West Broad St. Suite

500. Bethlehem, PA 18018

**All Rented firearms will be 12ga shotgun with shells unless specifically requested**

Friday, October 10, 2014

Lehigh Valley Sporting Clays

2750 Limestone St. Coplay, PA 18037

Check in and lunch will be available from 12:00 p.m. to 12:50 p.m. Please be at your cart

by 12:50 p.m. for any safety briefing by the course staff. A shotgun start is scheduled

for 1:00 p.m. The event will be held, RAIN or SHINE.

Please remember to return completed form and check to Frank Paretti by October 1st,

2014 by Noon.

PRIZE DONATIONS ARE WELCOME. Thank you in advance for your support!

Please forward any questions and completed forms to:

Frank Paretti - Lehigh Valley Engineering, 1 W. Broad St. Suite 500, Bethlehem, PA 18018

Telephone: (610) 704-2169 – Email: [email protected]

2nd Annual Lehigh Valley Chapter Sporting Clays Outing

Name: _________________________________ Tel: _______________________

Company: _________________________________ Fax: _______________________

Address: _________________________________ Email: ______________________

_________________________________ ______________________

Names of Participants:

Join in shooting- ______________________________ $

(See attached for pricing)

Guest: ______________________________ $

Guest: ______________________________ $

Guest: ______________________________ $

Total Amount Enclosed: (Make checks payable to Lehigh Valley ASHRAE) $

50 AS HRAE Jou rna l ash rae .o rg A p r i l 2 0 1 1

Corrosion problems are severe in marine refrigeration and air-

conditioning plants. Although corrosion can affect production in

commercial applications, in naval warships and submarines, corrosion

can affect the crew’s survival. This article discusses corrosion control in

marine refrigeration systems, but similar methodologies to control cor-

rosion are applicable for any refrigeration system.

The main types of corrosion occurring in marine refrigeration systems are elec-trochemical, galvanic, pitting, cavitation, stress concentration cracking, crevice, and fouling. Present and surrounding moisture also cause marine refrigeration systems to experience corrosion.

Electrochemical CorrosionIn metals, corrosion is caused by the

loss of electrons reacting with water and oxygen. Rusting, the weakening of iron due to oxidation of the iron atoms, is a well-known example of electrochemical

corrosion. This type of damage typically produces oxide(s) of the original metal. The corrosion can be uniform or local-ized and is not stable or self-healing.

With heat exchangers and pressure vessels, designers usually follow the guidance in various standards from such groups as the American Society of Mechanical Engineers (ASME) and the Tubular Exchanger Manufacturers Association (TEMA), etc. To control electrochemical corrosion, isolate the corroding metal from the corrosive en-vironment using paint and a protective

coating. Regular inspection and repair of the coating are necessary to achieve reliable and lasting protection.

Materials such as aluminium, titani-um, stainless steel and alloys are used in heat exchangers, pressure vessels, pip-ing, valves and accessories. In this case, a thin film of corrosion can form on the surface spontaneously. The oxide film is tightly adherent, stable and self-healing and isolates the surface from the corro-sive environment. The film acts as a bar-rier to further oxidation.

When the film stops growing at less than a micrometer thick, the metal be-comes passive toward further corrosion and the phenomenon known as passiv-ation occurs. In conditions where chlo-rine atoms are present (i.e., seawater), the ability to form a passivating film is hindered, and the film destabilizes, caus-ing pitting corrosion. Pitting corrosion

About the AuthorAmey S. Majgaonkar, M.E., is an assistant man-ager at Kirloskar Pneumatic Company Limited in Pune, India. He is a member of ISHRAE.

By Amey S. Majgaonkar, M.E.

Controlling CorrosionIn Marine Refrigeration Systems

This article was published in ASHRAE Journal, April 2011. Copyright 2011 American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. Posted at www.ashrae.org. This article may not be copied and/or distributed electronically or in paper form without permission of ASHRAE. For more information about ASHRAE Journal, visit www.ashrae.org.

Apr i l 2011 ASHRAE Jou rna l 51

is dangerous because it is less visible than rust. It often es-capes notice, and components fail inconspicuously. Care must be taken not to entirely trust passivation as a corrosion control mechanism. Periodic inspections are mandatory.

Galvanic Corrosion Galvanic corrosion is an electrochemical reaction between

two or more metals. One metal must be chemically more ac-tive (or less stable) than the others for a reaction to take place in presence of an electrolyte. Seawater, by virtue of its chlo-ride content, is an efficient electrolyte. Galvanic corrosion of a chemically more active metal (anode) can occur in the pres-ence of seawater. Anode material breaks away into the seawa-ter to produce oxides. These oxide molecules either drift away in the water or settle on the surface of the anode.

In marine refrigeration systems, galvanic corrosion occurs in heat exchangers, especially in seawater-cooled condensers, line valves and instruments such as pressure gages, and flow meters, which may be made of dissimilar materials.

Shell-and-tube condensers with shell-side fluid as the re-frigerant and tube-side fluid as seawater are generally used in marine refrigeration systems. To avoid galvanic corrosion, ideally, the same construction material should be used for tubes, tube sheets and water heads. However, in practice, a designer must choose different construction materials because of other constraints such as required heat transfer coefficients, malleability, ductility, castability, ease of manufacturing and cost. The construction material of seawater piping connected to the condenser also influences the galvanic corrosion and material selection. From a corrosion point of view, consider-ation given in the design of marine condensers can similarly be applied for brine chillers.

If the chosen materials differ widely in their electrode po-tentials, galvanic cells can form and destroy the anodic mate-rial. If copper is used for tubes and cupronickel is used in tube sheets in seawater-cooled condensers, copper tubes will cor-rode. Therefore, cupronickel tubes are used. Similarly, avoid threaded joints for materials that are far apart in the galvanic series.

The rate of corrosion depends on the ratio of areas of anode to cathode, water speed, temperature, alkalinity/acidity (pH of the water). However, the main factor is the difference in electrical potential of the two metals. The relative position of a pair of metals in Table 1 shows whether a corrosion prob-lem exists and whether an alternative choice of metal could be made sensibly. The relative surface areas of anode and cathode have a major effect on the rate of corrosion. If a large anode is connected to a small cathode, the anode will corrode slowly. However, if a large cathode is connected to a small anode, the anode will corrode rapidly. Table 1 also shows the varying potential of metals in seawater.1

Changing the potential of the metal to a point where corro-sion ceases can control galvanic corrosion. Impressed current cathodic protection (ICCP) systems or sacrificial anode sys-tems are used to change the potential.

ICCP systems use anodes connected to a dc power source. The current to the anodes must be controlled to maintain the set voltage required. An ICCP system is used when the protec-tive cathodic current requirement is high. Since marine refrig-eration systems are relatively smaller than other larger marine structures (such as the underwater hull surface), an ICCP sys-tem normally is not used.

In a sacrificial anodes system, anodes enable the potential of the system to be changed. The system provides temporary protection to metal, which is made to behave as a cathode. It is most suitable for marine refrigeration systems as it does not require an external electric power supply nor any control by operating staff.

The first step in the design of a condenser cathodic protec-tion system is the estimation of protective cathodic current re-quirement.2,3,4 The procedure involves calculation of exposed water box and tube sheet areas. Current flows in an elliptical path inside a tube or pipe. The effective length of the tube/pipe, to be taken in area calculation, is approximately twice the diameter of the tube/pipe. The design current density needs to be determined from past experimental data or from per-

Potentials In Seawater Against A Silver/Silver Chloride Electrode

Material Potential (V)

Magnesium (–) 1.6

Zinc (–) 1.0

Aluminum Alloys (–) 0.9

Cadmium Plating (–) 0.8

Mild Steel (–) 0.6

Cast Iron

Stainless Steel (–) 0.5

Brass

(–) 0.3Copper

Aluminum Brass

Nickel Aluminum Bronze

(–) 0.2Aluminum Silicon Bronze

Gunmetal and Cupro Nickel

Nickel

(–) 0.1Silver

Stainless Steel (Passive)

Monel 0

Titanium(+) 0.1

Ferralium

Platinum (+) 0.2

Graphite (+) 0.3

Table 1: Galvanic series shows varying potential of metals in seawater.1

52 AS HRAE Jou rna l ash rae .o rg A p r i l 2 0 1 1

forming actual field experiments. This is complex and designers prefer to use past experience for their determination.

The range of current outputs for dif-ferent sacrificial anode materials with standard dimensions is generally known or can be obtained from the anode man-ufacturers. The number of anodes can be determined from total estimated current requirement divided by current per an-ode. It is important to maintain electri-cal continuity of the anode during instal-lation.

Considering the feasibility for accom-modating the number of anodes in the water heads, suitable anode material can be chosen to restrict the number of anodes. Selection of sacrificial anode material also depends upon the degree of protection required, cost of anode material and its rate of consumption by corrosion. Carefully balanced zinc al-loy, which corrodes evenly at a steady rate, is preferred as sacrificial anodes in marine condensers. Magnesium anodes can also be used but because of their higher driving voltage they are quickly spent. Systematic location of the anodes is critical to their overall effectiveness. The location of anodes is generally de-cided using past experience, ease of maintenance and symmetry. The anodes must be regularly serviced and replaced when spent.

In seawater cooled shell-and-tube condensers, anode rods are provided in the water heads, typically in two ways, as shown in Photos 1 and 2.

Photo 1 shows the anode rods com-pletely inside the water head. The ad-vantages of such an arrangement are that the depth of water heads can be minimized to reduce the overall length of the condenser and leakages through the anode holding holes in water heads can be avoided. The length limitations are critical for naval duty as less space is available onboard. The leakages can be severe in some cases, such as with seawater-cooled condensers onboard a submarine, because seawater pressure is in the range of 20 to 30 bars (2000 to 3000 kPa).

The major disadvantage is that you must open the condenser water heads to

Photo 1 (top): Anode rods inside water head. Photo 2 (bottom): Provision to insert anode rods in water head from outside.

know the status of the anode rod corro-sion.

In Photo 2, a provision is made to insert the anode rods in the water head from the outside. The advantage is that the operator can easily determine the corrosion status of the anode rod by removing only the anodes. The disad-vantage is the depth of water heads are

increased, causing an increase in the overall length of the condenser and the chance of leakages through the anode holding holes in the water heads.

A common maintenance problem with this arrangement occurs when operation and maintenance staff use these anodes as handholds and footholds. The staff must be trained and prohibited from do-ing so, as the anodes may break inside the waterhead.

In some cases, anodes are provided even after using the same construction material for tube sheets, tubes, water heads and seawater piping. The corrosion of anodes in these cases does not indicate any sacrifice, as galvanic corrosion of the base metal is not probable even if an-odes are absent. Thinking that the anode rods are protecting condenser corrosion, the operator will continue to replace the consumed rods unnecessarily. Designers should avoid such redundant selections, which confuse operators.

Seawater pipelines may be made of a variety of materials: titanium, copper, nickel, etc. When connecting pipelines of different materials, use flange joints with gaskets to electrically insulate the two materials. Electrical discontinuity must be maintained between the two pipes. Therefore, flange bolts must be rubber coated, plastic/rubber washers should be used and the pipe should be supported using clamps with internal rubber lining. The electrical discontinu-ity between metals prevents electrons from flowing and causing galvanic cor-rosion. Over a period of time, a salt bridge can form in a flanged joint, which allows galvanic corrosion. The pipe should be cleaned periodically from the inside to avoid salt deposition.

Pitting Corrosion Pitting corrosion is a form of ex-

tremely localized corrosion that leads to the creation of small holes in the metal. This kind of corrosion is insidious. It causes little loss of material, showing a small effect on its surface, while it dam-ages the metal deep inside. Corrosion often obscures the pits on the surface and makes pitting difficult to detect.

All forms of pitting are caused by the same basic mechanism. During corrosion, the protective film may not form or local destruction of film may occur. This local void in the protective surface can set up a galvanic cell. In a local galvanic cell, lack of oxygen around a small area creates an anode. The area with excess oxygen be-comes a cathode. The corrosion penetrates the mass of the metal, with limited diffu-sion of ions, further pronouncing the lo-calized lack of oxygen.

54 AS HRAE Jou rna l ash rae .o rg A p r i l 2 0 1 1

pitting. During a prolonged shutdown of a plant, the seawater remains stagnant in condenser water heads, inducing pitting. Properly located and sensibly operated drains help avoid pit-ting. Weep holes on the pass partition plate (Figure 1) allows the water to fall in the lowest pass where it can be drained.

Metals with impurities caused by cold working, welding, or alloys with microstructures consisting of two different metal-lurgical phases are generally more prone to pitting. Alloys most susceptible to pitting corrosion are where corrosion resistance is caused by a passivation layer such as stainless steels, nickel alloys or aluminum alloys. Metals susceptible to uniform cor-rosion tend to not have pitting. Regular carbon steel corrodes uniformly in seawater, while stainless steel will pit. The addi-tion of about 2% of molybdenum increases pitting resistance of stainless steels. Corrosion inhibitors, when present in sufficient amounts, provide protection against pitting. However, if the lev-el is too low, they can aggravate pitting by forming local anodes.

Another type of pitting corrosion rarely found in marine re-frigeration systems is formicary corrosion, which forms on refrigerant copper pipelines and heating cooling coils. The corrosion appears as multiple pinhole leaks at the surface of the copper tube that are invisible to the human eye. Upon microscopic examination, the formicary corrosion pits show networks of interconnecting tunnels through the copper wall. This network resembles an ant nest.

Formicary corrosion occurs in the presence of moisture and organic acids such as formic and acetic acid. These acids are present in insulation, adhesives and paint. Using formic and acetic acid-free insulation, adhesives and paint can minimize such corrosion. Other sources of formic and acetic acid in-clude plants onboard in dry dock, as well as smoke, fumes and paint particles, which may be trapped below the insula-tion. Properly ventilate the compartment before insulating the refrigerant copper lines.

CavitationCavitation is the formation of vapor bubbles of a flowing

liquid in a region where the pressure of the liquid falls below

its vapor pressure. Cavitation is the process where a void or bubble in a liquid rapidly collapses, producing a shock wave. Strong shock waves formed by cavitation removes the metal by erosion. Such cavitation often occurs in pumps, propellers and impellers.

Cavitation occurs in the seawater or chilled water pumps used in marine refrigeration systems. The operator will know cavitation is occurring when the pump produces a knock-ing noise and vibrations while increasing power input and decreasing pump output. The pump must be stopped imme-diately to avoid damage to the impeller and casing. Before stopping the pump, always remember to stop the compressor to avoid damage to it. The pump can then be inspected for damage.

The pressure required to operate a pump without causing cavitation is called net positive suction head (NPSH). The pressure head available at the pump inlet should exceed the required NPSH. The pump manufacturer specifies the NPSH.

As cavitation relates only to the suction side of the pump, all prevention measures should be directed at this area. The following guidelines should be used:

• Minimize the pressure drop in pump suction line; • Minimize number of valves and bends in the pump suc-

tion line; • Suction length (lift) should be as short as possible; • Suction pipe should be at least the same diameter as the

pump inlet connection; • Use long radius bends; • Increase the size of valves and diameter of pump suction

pipe; • Do not allow air into the pump suction line; • Ensure adequate submergence over the foot valve; • Try to install the pumps always below the water line; • If possible, make self-priming provisions; and • One solution may be to reduce the required net positive

suction head. Lowering the pump speed can do this. However, this will also result in reduced output from the pump, which may not be suitable for the system.

Tube SheetEnd

CoverShell Refrigerant

Vapor InSupport

Plate Tubes

Seawater

Out 97°F

Seawater

In 90°F

Condensation at 104°F

Refrigerant Liquid Out

Weep Hole

Cathodic Protector

Figure 1: Typical marine condenser.

In marine refrigeration systems, the pitting corrosion is observed in piping, valves, pumps, and condenser water heads, etc. Pipes welded to-gether may have a variation in composition, causing pit-ting. The paint and coating on pipelines usually breaks on the support because of vi-brations. Therefore, this dis-continuity causes pitting. If possible, provide pipe clamps with an internal rubber lin-ing to avoid friction damage to pipes. Polished surfaces display higher resistance to

56 AS HRAE Jou rna l ash rae .o rg A p r i l 2 0 1 1

If cavitation cannot be eliminated at the design stage, se-lect suitably resistant alloys. For detailed guidelines for pump design and material selection, refer to the U.K. standard in Reference 5.

Stress Corrosion Cracking Stress corrosion cracking (SCC) is the unexpected sudden

failure of normally ductile metals subjected to a tensile stress in a corrosive environment, especially at an elevated tempera-ture in the case of metals. It is more common among alloys than pure metals. High levels of stress in service, or residual stress from manufacturing may result in selective corrosion of more highly stressed regions of an otherwise corrosion re-sistant structure. In the aggressive marine environment, even the more resistant alloys may be affected by hydrogen-induced cracking, or by chloride or sulphide stress corrosion cracking.

The stresses can be the result of the crevice loads due to stress concentration, or can be caused by the type of assembly or residual stresses from fabrication (e.g., cold working). An-nealing can relieve the residual stresses.

Although not a widespread problem, failure from stress cor-rosion can occur where both stress, internal or external, and a corrosive environment are present. The corrosion is specific to the material and its environment, and stress, whether im-posed or residual internal, must be tensile. The mechanism differs according to the material and the environment but fail-ure would not occur if either stress or corrosion were absent.

Cupronickel has a good resistance to stress corrosion crack-ing and is not susceptible to chloride or sulphide or ammonia in seawater, which is why it is normally used in seawater pip-ing for marine refrigeration systems. The refrigerant piping can be provided with flexible vibration eliminators to avoid pipe stresses during operation.

It is generally understood that stress corrosion cracking oc-casionally can affect high-pressure vessels in ammonia refrig-eration systems. But research suggests that it is not restricted to high-pressure vessels and may affect copper pipe work in fluorocarbon refrigeration systems.6 One method to reduce the probability of stress corrosion cracking is to control the temperature. Using liquid refrigerant injection with screw compressors can control discharge temperature. Removing non-condensable gases by proper purging reduces the con-densing pressure and temperature. Titanium and its alloys are resistant to stress corrosion cracking in most media, includ-ing marine environments. However, certain titanium alloys are susceptible to stress corrosion when in contact with chlori-nated hydrocarbons or fluorinated sealants.7

Crevice CorrosionCrevices can develop a local chemistry, which is different

from that of the bulk fluid. For example, in boilers, concen-tration of non-volatile impurities such as sodium, sulfate or chloride may occur in crevices near heat-transfer surfaces be-cause of the continuous water vaporization. Fouling of heat exchangers also can cause crevice corrosion in marine refrig-

eration systems. Common locations for crevice corrosion in heat exchangers are at gaps between the tube and tube sheet or at gasket joints.

Two factors are important in the initiation of active crevice corrosion. First, the higher concentration of the electrolyte in the crevice. And, second, the differential electrolyte chemistry inside and outside the crevice (a single metal part undergoing corrosion is submerged in two different environments).

Both factors are caused by deoxygenation of the crevice. Some of the phenomena occurring within the crevice may be somewhat reminiscent of galvanic corrosion.

To prevent crevice corrosion, you need to eliminate the crevices by using welded butt joints instead of riveted or bolt-ed joints, performing continuous welding or soldering, rather than lap joints, as well as using non-absorbent gaskets such as Teflon can reduce crevice corrosion.

Fouling Fouling is accumulation of unwanted material on solid

surfaces, most often in an aquatic environment. In marine re-frigeration systems, fouling can occur in heat exchangers, es-pecially in a shell-and-tube condenser and an evaporator and water pipelines. Fouling phenomena are common, complex and diverse. Unlike corrosion, fouling leads to high opera-tional losses by inefficient heat transfer and increased pressure drop. To compensate for fouling, heat exchangers are liberally sized, which results in higher capital cost. There are also in-creases in inspection and maintenance costs.

The indirect damages arise from using biocides and in-creased energy or fuel consumption. Fouling also causes many additional problems like corrosion damage, flow blockages/redistribution, flow induced vibrations, etc. The fouling mate-rial can consist of either living organisms (biofouling) or a non-living substance (inorganic or organic).

Biological Fouling. Biological fouling is an undesirable accumulation of organisms such as algae, bacteria, diatoms, plants, and animals on surfaces. Calcareous organisms attach to the base surface using different types of glues. These are sticky holding mediums for other types of fouling, which oth-erwise would not adhere to clean surfaces.

Biofouling of marine heat exchangers, water pipelines, etc., promote corrosion. Filtration, chlorination and biocides are necessary to prevent frequent shutdowns.

Non-Biological Fouling. This fouling may occur by precip-itation, sedimentation, coagulation and chemical reaction. At a higher temperature, calcium bicarbonate present in the water decomposes to form calcium carbonate and its precipitates. The scaling is higher at the hotter outlet of a heat exchanger than at the cooler inlet. Maintaining lower discharge and con-densing temperature can help delay scaling.

A chemical fouling inhibitor can interfere with the crys-tallization, attachment, or consolidation steps of the fouling process. In addition, additives may alter the structure of the fouling layers so that they can be removed easily. However, chemical cleaning methods are not practical in marine re-

Apr i l 2011 ASHRAE Jou rna l 57

frigeration systems as cooling water is continuously pumped from and discharged into the sea. If this method is used, only evironment-friendly chemicals should be used. Chemical cleaning must be followed by passivation of the surfaces.

Fouling ControlTemperature Control. As the discharge gas/condensing

temperature increases, the amount of fouling increases. Op-erating the plant at a lower discharge/condensing temperature can delay scale buildup.

Velocity Control. Marine condensers are often a shell-and-tube design, using seawater as the condensing medium; re-frigerant flows on the shell side, and seawater flows through tubes. Higher seawater velocities reduce the tendency to foul; however, velocities are limited by erosion. Using harder tube materials such as cupronickel and titanium can allow higher velocities to be used without much erosion.8,9 The higher velocities also increase pressure drop and pumping power. Therefore, the designer must optimize capital cost, operating cost, erosion and corrosion.

The stagnant regions in the water heads require properly located drain plugs. Because of rolling and pitching, the size and number of drain plugs must be sufficient to drain the seawater freely. Webs, or pass partition plates, are used for making passes on the tube side in the condenser. The provi-sion of weep holes on the webs in water heads allows the water to flow to a lower pass from where it can be drained out. (Figure 1).

Direct expansion (DX) chiller packages are often used in marine refrigeration systems; water flows on the shell side and refrigerant flows through tubes. High velocities on the shell side are limited by flow-induced vibration. Properly spaced baffles help minimize the dangers of flow induced vibrations.

Material Selection. Selection of tube material is important for the required heat transfer rate and is significant from a cor-rosion point of view. Copper bearing tube materials can lessen certain kinds of biological fouling. Generally, copper tubes are used for a DX evaporator with fresh water flowing outside the tubes. Cupronickel/titanium tubes are used in condensers with seawater flowing through the tubes.

Because the refrigerant side governs the heat transfer co-efficient, the condenser tubes are externally finned and the evaporator tubes are internally finned. The surface finish also influences the rate of fouling and ease of cleaning. The heat exchangers must be situated so that enough space is available for tube cleaning. This is particularly important in warships and submarines.

In some applications where seawater is used on the shell side, tube sheets and tubes can be constructed using cupro-nickel. Since cupronickel is a hard material, internal finning can be difficult. Plain tubes require more surface area for the same heat transfer duty.

Filtration helps in removing macroparticles and prevent-ing deposition and fouling. The filters must be inspected and

cleaned periodically; partially clogged filters can cause huge operational losses. A clogged condenser water filter results in increased condensing temperature and compressor power. Higher surface temperatures cause increased fouling deposits.

Prevention of Biological Growth. Fluid treatment is com-monly carried out to prevent corrosion and/or biological growth. However, the effect of biocides on the environment should never be ignored.

Place More Fouling Fluid on Tube Side. Two benefits oc-cur from placing more fouling fluid on the tube side. There is less danger of low velocity or stagnant flow regions, and it is generally easier to clean the tube side than the shell side. It is often possible to clean the tube side with the exchanger in place, however, it may be necessary to remove the bundle to clean the shell side.

Design Fouling Resistances (ft2·h·°F/Btu). The values of fouling resistances do not recognize the time-related behav-ior of fouling with regard to specific design and operational characteristics of a particular heat exchanger. Fouling resis-tance, as per TEMA, is generally used if any other value is not specifically mentioned. Advanced heat exchanger design software allows for the design of better heat exchangers.

Corrosion by Moisture Present in the SystemReasons for presence of moisture in any refrigeration sys-

tem are incomplete drying of components during manufactur-ing, moisture left in the system after evacuation or dehydra-tion during installation, moisture content in refrigerant and oil and formation of moisture or water due to a chemical reaction within the system.

Moisture in the system can react with halogenated refriger-ant and form hydrochloric or hydrofluoric acids. These acids, particularly hydrofluoric acids, are very active and highly cor-rosive, and they attack various parts of refrigeration systems. The compressor motor winding in a sealed unit is usually the first to be affected by acids and moisture. A peculiar pungent smell coming from the gas of a burned-out, sealed-unit system is due to the presence of hydrofluoric acid.

Because chemical reactions due to acids and moisture are accelerated at higher temperatures, discharge valve reed and seats become corroded easily. Damaged discharge valve reed and seats will cause a decrease in compressor efficiency and allows hot discharge gas to flow back to the suction side. This raises the compressor body temperature and causes further corrosion. Corrosion products can contaminate the lubricat-ing oil and deteriorate its lubricating properties. The life of bearings and journals will decrease, and even compressors can completely fail.

In a low-temperature application, such as refrigeration plants, the presence of moisture in the system is quickly de-tected by the freezing of moisture at the throttling device and consequent malfunctioning of the refrigeration system. In ap-plications such as air conditioning, the evaporating tempera-ture is above 0°C (32°F) and the presence of moisture in the system is not evident at all. The system components are af-

58 AS HRAE Jou rna l ash rae .o rg A p r i l 2 0 1 1

fected, but is only evident when the system fails. It is impor-tant to remove the moisture from the system. Following deep dehydration and evacuation of a refrigeration system during installation can significantly remove the moisture from the system. Any traces of moisture can further be countered by providing a filter drier in the refrigerant liquid line. The core of the driers should be regularly replaced.

Corrosion by Moisture Surrounding the SystemIn marine refrigeration plants moisture present outside the

system also causes considerable corrosion. Corrosion under insulation (CUI) of carbon steel pipes and the evaporator shell10 is a typical example of corrosion by moisture sur-rounding the system. Unfortunately, CUI is difficult to detect as the metal surface is covered under insulation. The water formed from condensation of moisture expands during freez-ing and damages the insulation. The damaged insulation be-comes more susceptible to further corrosion. All joints and surfaces should be carefully sealed to keep out atmospheric moisture. Applying corrosion resistant paint and installing a good closed cell insulation material that is tightly bound to the pipe can help control CUI.

During maintenance, the damaged insulation should be in-spected, repaired or replaced. In refrigeration applications be-low 0°C (32°F), a proper drain arrangement with defrost heat-ers must be provided. The electrical panels should incorporate space heaters. The cable entry11 to electrical panels should be placed to avoid any chances of water dripping inside. The IP Codes or International Protection Rating for electrical equip-ment must be followed.

Corrosion Control in Piping and DuctsCorrosion affects refrigerant piping, chilled and seawater

piping and HVAC&R ducts. The higher flow rates in chilled and seawater piping and in

seawater tubes are limited by erosion. But low flow rates are also damaging and cause under deposit corrosion.12 Erosion problems in condenser water heads can be minimized by siz-ing the water heads for 10% to 15% extra capacity and care-fully deciding the nozzle entry.

Selecting suitable corrosion resistant construction mate-rial controls corrosion of chilled water and seawater pip-ing. Titanium and cupronickel pipes allow higher veloci-ties without erosion problems. However, these materials are costly. The pipes can be joined together by flanges and stubends. With this arrangement, flanges are prevented from coming in contact with seawater. Therefore, carbon steel flanges and cupronickel stubends are common for ma-rine applications. This also helps reduce capital costs con-siderably.

Steel sheets are used to make air ducts. To inhibit corrosion during transportation and storage of the ducts, they are coated with a thin film of oil. However, this coating may trap dirt par-ticles and cause problems with ensuring acceptable indoor air quality. Before installation, remove the oil coating by washing

with a soap solution. Routinely inspect the duct for moisture-induced corrosion damages.

Refrigerant piping is joined by welding and brazing. Both processes are heterogeneous and are susceptible to microgal-vanic corrosion. The joints retain residual stresses and matrix heterogeneity. Heating these joints to appropriate tempera-tures, which are below the transformation temperature range, may reorganize the microstructure uniformly and deactivate the highly stressed sites. Such structural uniformity and stress matching reduces the microgalvanic corrosion.

Summary Designers can tackle corrosion problems by designing heat

transfer processes better, controlling the flow behavior of flu-ids involved, selecting corrosion resistant construction materi-als and choosing appropriate manufacturing methods. In ad-dition, designers also need to consider ease of inspection and maintenance and optimization of capital and operating costs. A designer’s dream can become a reality only by proper instal-lation and operation of a system. Hence, care must be taken during installation and operation to minimize corrosion.

AcknowledgmentsThe author wishes to thank Kirloskar Pneumatic Company

Limited, Pune, India, for providing an opportunity to learn and design marine refrigeration and air-conditioning systems.

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4. Det Norske Veritas. 2005. “Recommended Practice DNV-RP-B401, Cathodic Protection Design.”

5. U.K. Ministry of Defence. 2006. U.K. Defence Standard 02-327, Requirements and Guidance for the Procurement of Pumps for Auxiliary Systems.

6. Pearson, A. 2008. “Stress corrosion cracking in refrigeration systems.” International Journal of Refrigeration 31(4):742 – 747.

7. U.K. Ministry of Defence. 2007. U.K. Defence Standard 00-970 Part 7/2, Design and Airworthiness Requirements for Service Aircraft, Section 4 Detail Design and Strength of Materials.

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