Piping New

8/12/2019 Piping New

1/31

qwertyuiopasdfghjklzxcvbnmqwertyupasdfghjklzxcvbnmqwertyuiopasdfghzxcvbnmqwertyuiopasdfghjklzxcvbnm

wertyuiopasdfghjklzxcvbnmqwertyuioasdfghjklzxcvbnmqwertyuiopasdfghjkxcvbnmqwertyuiopasdfghjklzxcvbnm

wertyuiopasdfghjklzxcvbnmqwertyuio

asdfghjklzxcvbnmqwertyuiopasdfghjkxcvbnmqwertyuiopasdfghjklzxcvbnmwertyuiopasdfghjklzxcvbnmqwertyuioasdfghjklzxcvbnmqwertyuiopasdfghjkxcvbnmqwertyuiopasdfghjklzxcvbnmwertyuiopasdfghjklzxcvbnmqwertyuioasdfghjklzxcvbnmrtyuiopasdfghjklzxc

bnmqwertyuiopasdfghjklzxcvbnmqweyuiopasdfghjklzxcvbnmqwertyuiopasghjklzxcvbnmqwertyuiopasdfghjklzxc

bnmqwertyuiopasdfghjklzxcvbnmqwe

yuiopasdfghjklzxcvbnmqwertyuiopas

Piping interview questions and answers

QA/Q

ANES


2/31

Examination:

It applies to quality control function performed by the manufacturer, fabricator or erector for componentsonly. Responsibility for examination:

Inspection does not relieve the manufacturer, the fabricator or the erector of the responsibility forA. Providing materials, components and wormanship in accordance with the requirements of this

code and of the engineering design.!. Performing all required examination.". Preparing suitable records of examinations and test for the inspector#s use.

Inspection:

Inspection applies to functions performed for the owner by the owner#s inspector or the inspector#sdelegates. Responsibility for inspection: $o verify that all required examination and testing have been completed and to inspect the

piping to the extent necessary to be satisfied that it confirms to all applicable examination requirements ofthe code and of the engineering design.

%aterials shall have the strength and ductility at which temperature and pressure material has beendesigned. %ore over, service fluid also shall be considered while selecting the material.

Welding:

It is a metal &oining process by applying heat to the melting temperature of base metal and filler metal.'iller metal may not be used. (ow carbon steels ) *+*+ to *+- degree c %edium carbon steels */-0 to *+*+ degree c 1igh carbon steels */2+ to */-0 degree c 3tainless steels */22 degree cSoldering:

$he melting point of the filler metal is less than /04 degree cBrazing and braze welding:

$he melting point of the filler metal is above /04 degree c.!ut below the melting point of the basemetal.

In bra5ing and soldering, the filler metal is being distributed between the two closely ad&acentsurfaces of the wor pieces by capillary action. !oth soldering and bra5ing processes are particularly usefulfor &oining two dissimilar metals. In bra5ing process, large amount of diffusion will tae place in order to strengthen and improve the

bond, where as, in soldering, diffusion is secondary in importance. 3oldered &oints do not resist corrosion.

Cutting processes:

"utting is accomplished by applying heat to the part using the preheat flame which is an oxyfuel mixture.$he metal has been heated to its oxidation temperature 6indling temperature78 the cutting oxygen is turnedon to oxidi5e the hot metal. $he oxidation of the metal produces a tremendous amount of heat. $hisexothermic chemical reaction provides the necessary heat to rapidly melt the metal and simultaneously blowthe oxidation products from the &oint. $he width of the cut produced is referred to as the erf.

In "3, the indling temperature is lower that than melting temperature 6-0+degree c7. In alloy and 33, the indling temperature is higher than melting temperature. 9xides of many alloying elements in steels, such as chromium and aluminium, have melting pointsmuch higher than those of iron oxides. $hese high melting point oxides which are refractory in nature shieldthe material in the erf and the speed of cutting decreases because fresh iron is not continuously exposed tothe cutting oxygen stream.

Difference between AC and DC power sources:

A" gives a smoother arc at higher arc current, there is no arc blow.$he arc can be easily maintained and controlled.


3/31

$he melting rate of the electrode can not be controlled, because of heat generation at electrode and &ob willbe equal. 3o it is suitable for welding thicer sections.o noise because of not having rotating part.(ow cost and high efficiency 6.;7"onsume less energy.3ingle phase transformer supply low currents. 3o it is used for welding thinner sections with small diameter

electrodes.$wo phases and three phase supply transformers supply high currents and are used for thicer &obs welding.In A" more than one operator can wor.A" welding transformer 6constant current power source7 possesses drooping characteristics. "urrent rangeup to /+ to 4+.=" generator is air cooled. A transformer cum rectifier unit may be cooled by forced air circulation.

Rectifier is used to change A" to =". transformer is used to increase the current and decrease thevoltage and vice versa.Preeating is aimed at

*. 3lowing down the cooling rate of deposited weld metal and 1A? so as to "ontrol the martensiteformation, reduce hardness and brittle areas. 0. Improving the diffusion of gas molecules through out atomic structure so as to avoid the embrittlenessin 1A? and hydrogen induced cracing.

. "ontrolling the effects of expansion and contraction. /. Avoiding the thermal shoc. 9$@: $he temperature requirements are basically based upon carbon

@quivalent and thicness.

Inter pass eatingis aimed at*. %aintaining the notch toughness of ferritic steel or the corrosion resistance of austenitic stainless steel

and some non ferrous alloys.0. Protecting the health and effectiveness of the welder.

Post eatingshall be performed while*. oining high strength and alloyed steel 6other than austenitic stainless steels7.0. Introducing hydrogen from the welding consumables or base metals is not adequately controlled.. Preheating or interpass heating is not sufficient.

$he primary ob&ective for post heating is the removal of hydrogen and the prevention of hydrogeninduced cracing.

PW!"is generally aimed at *. Improving resistance to brittle fractures by improving notch toughness and relax residual stresses. 0. $empering martensite in order to restore the ductility. . Improving corrosion resistance and reducing hardness depending upon the environment.

Soa# band:

$he soa band consists of the through thicness volume of metal, which is heated to minimum. !utdoes not exceed the maximum required temperature. As a minimum, it should consist of the weld metal,1A? and a portion of the base metal ad&acent to the weld being heated.


4/31

%inimum recommended soa band width for preeating$interpass eating is inch 64+mm7 or *.+t,whichever is greater in all directions from the point of welding.%inimum recommended soa band width for ba#e outis


5/31

Selection of termocouples:

9ne should consider the response time as well as the durability, loop resistance of the circuit,chemical corrosion, radiation effects and stability. A voltage difference bet the two &unctions is created with one wire serving as a positive electricallead and the other as the negative lead. $he voltage difference is proportional to the differences intemperature.

$he measurement accuracy depends on heat transfer from the wor piece to the bead &unction.Control termocouples:

$he location of control thermocouples should be based upon the nature of the heat source,locations of heat sources and the component being heated. $he control thermo couples would most liely be

placed along the center line of the weld in the middle of the center heater of the control 5one.

'onitoring termocouples:

%onitoring thermocouples should be placed to insure that all of the parameters specified tocontrol the local heating operation are being achieved. $hermocouples should be placed at the center line ofthe weld, edge of the soa band and at the edge of the heated band. If there is access, it is always good

practice to locate thermocouples inside surface of the pipe to insure that the required temperature is achievedthroughout the thicness.

"enter line of the weld )insure that the maximum temperature is not exceeded.edge of the soa band determine if the minimum temperature have been achieved throughout the soa band.edge of the heated banddetermine if the maximum allowed temperature drop

6%aximum axial temperature gradient has been@xceeded7Insulation:

It is generally utili5ed to minimi5e heat loses from the out side surface to the surrounding air and tominimi5e axial temperature gradients. Insulation should be placed on the inner surface of the pipe to reduce the throughthicness temperaturegradient which results from radiation and convection heat loses from the inner surface.

lass wool ;/2' 6/+2c7 Roc and slag 6mineral7 wool *022' 6


6/31

!eating rate:

Hith an external heat source, the existence of a throughthicness temperature gradient produces hoopstresses. $he stresses are proportional to the temperature difference between the out side and inside surfaces. Asthe heating rate increases, the temperature difference increases. %aximum recommended heating rate for PH1$ is ;22'Bhr 6///cBhr7 divided by the thicness in

inches.!old time and temperature:

Prolonged time at PH1$ temperature can reduce tensile and yield strength and increase the fracturetransition temperature. $he total time at temperature is ;2K of the total time at temperature during all actualheat treatment cycles.Cooling rate:

3tresses induced during heating are liely relaxed during the hold period and cooling. residual stressesare generated as a result of temperature differences which are sufficient to induce thermal stresses in excessof the yield strength. As temperature decreases, the yield strength of the material increases. $he cooling ratemay also affect mechanical properties such as impact toughness and corrosion resistance. Procedures havespecified slower cooling rates because of a decrease to insure greater hardness reduction. $he most effectivemethod to accomplish greater hardness reduction is to increase the hold temperature. =ecreasing the rate ofheating would have a greater effect than decreasing the rate of cooling. %aximum recommended cooling ratefor PH1$ is +22'Bhr 604;cBhr7 divided by the thicness in inches.

Interruption during eating:

1eating can be restarted at the heating rate appropriate to the temperature at restart. $here is no needto return to ambient temperature and restart the heating.

Interruption during old period:

Hhen the temperature drops below the minimum for soa before the end of the required hold time,the first response should be to correct the cause of the interruption. 1eating is then restarted at a rateappropriate for the temperature of the pipe at restart. 9nce at or above the minimum soa temperature, holdis resumed and maintained for a period of time such that the summation of all time periods at or above theminimum soa temperature should be equal to or greater than the minimum required.

If the temperature does not exceed the lower critical temperature, reduce the temperature to the soarange at a cooling rate no greater than the maximum allowed and hold for the remaining required time. Alltime above the minimum temperature, including that above the maximum temperature, can be used todetermine the total time at temperature.

Interruption during cooling:

If the cooling rate is high, the distortion andBor introduction of residual stresses would occur. Ifdistortion occurs, it would have to be assessed after returning to ambient temperature. $o repeat all or a

portion of the hold period, heating should be restarted with a heating rate appropriate to the temperature ofthe piping at restart. 1eating should continue until the minimum soa temperature is achieved. 'or certainmaterials such as ferritic stainless steel, a fast cooling rate 6specified as a minimum rate7 may be required toavoid embrrittlement or other undesirable metallurgical reactions.

Excessi)e eating or old time during PW!": "ertain materials may have their properties adversely affected by prolonged times during the heatingor hold portions of PH1$ cycle.PH1$ can be applied number of times on the basis of the specific thermal8cycles 6temperature and time7, material 6composition of weld metal and base metal8 heat treated condition ofthe base metal7, governing properties 6toughness etc7 and the response of the weld metal, heat affected 5oneand base metal. If recogni5ed early, the best response to a deviation associated with excessive heating or holdtimes is to change the setup and or equipment. $his obviously requires aborting the PH1$ cycle, returningto ambient temperature and would typically result in a schedule delay.


7/31

Considerations related to ser)ice en)ironment:

$he environment or corrosion reactions result in diffusion of atomic hydrogen into the base metaland weldment.in high strength or high hardness areas, this hydrogen can result in 13". Reducing weldmenthardness and residual stresses is believed to reduce the lielihood of this stress oriented hydrogen inducedcracing 6391I"7.

3everity of cracing is often dependent on temperature,concentration,level of residual stresses, and

other factors."ontroling weldment hardness does not prevent Alaline stress corrosion cracing6A3""7because high tensile stresses may still be present. @nvironmental cracing 6both 13" and A3""7 has initiated from preexisting weldmentfabrication defects. 1ence, during original fabrication, weldments should be inspected for defects such aslac of fusion, delayed hydrogen cracing, or severe undercut. Any defects found should be removed. In %AH, welding using "90 mixtures, oxygen generated by breadown of the "90 causesoxidation of %n and 3i in the weld metal, thus reducing the concentration of these elements in the welddeposit matrix. Reductions of 2. wtK in the %n and .20wtK in 3i are common in %AH deposits

produced using *22K"90. Hhen required, hardness testing in completed welds shall be done after any PH1$. Preheating and high heat inputs during welding are generally beneficial in reducing weldmenthardness because they reduce the cooling rate the weldment. 3mall fillet welds on large sections are often prone to high 1A? harness. $his is because suchwelds often have low heat inputs and large sections act as significant heat sins that result in high coolingrates. 9ne example is trayattachment welds in vessels. $he highest hardness in weldments is generally in the 1A? of the last weld pass. 'or all welding processes, the heat input during production welding should not vary by more thanE02Kand *2K from the heat input used on the test sample. Preheat and interpass temperature used during production welding should be greater than or equalto that used in the welding procedure qualification tests. A3"" generally has three requirements: a cracinducing environment, a susceptible material and atensile stress. residual tensile stresses are usually highest in the 1A?, but can sometimes extend up to +2 mm60.2in7 away from the weld deposit. 1ence, these are the most common locations for A3"", with the cracstypically oriented parallel to the weld.weldment hard nesses usually have no effect on A3""susceptibility.PH1$ is an effective method of mitigating A3"".this is because PH1$ has two primary

benefits: lowering weldment hardness 6that helps resist 13"7 and reducing residual stresses from welding.!y reducing residual stresses, PH1$ helps prevent A3"".

'or improving cracing resistance in amine and caustic services, an effective procedure consists ofheating weldments to ariables affecting the depth of residual stresses are welding heat input, base material thicness andattachments weld si5e.

$he peening stress relief process should not be used for applications in A3"" environments becauseof the limited success of this technique in corrosive service. A concern is that shot peening produces asurface layer with compressive stresses, and this layer may eventually corrode away exposing subsurfacematerial that still has residual tensile stresses. Alternative welding methods such as temper bead welding and controlleddeposition welding are not

effective in mitigating A3"". these methods do not sufficiently reduce residual stresses, and thereforeshould not be considered in lieu of thermal stress relief.

Appropriateness of furnace and local PW!":

Increasing the heated band width and decreasing the axial temperature gradient can be used to reducethe magnitude and shift the pea induced stress axially away from the weld centerline for local


8/31

"empering and stress relaxation ob*ecti)es:

$he soa band should be large enough to accommodate the regions where tensile residual stresses arepresent. $he tensile residual stresses may be present up to 0inch 6+2mm7 from the weld as per A"@RP2/40.

!ardness testing:

1ardness testing of production welds is commonly used as a quality control tool to insure thatadequate local PH1$ has occurred. 3uch testing may be specifically aimed at insuring that adequatetempering has occurred during PH1$ to mitigate hydrogen stress cracing.

Induction eating stress impro)ement +I!SI,:

A speciali5ed local heating technique was devolved to address intergranular stress corrosion cracing6I3""7 of welds in austenitic stainless piping in boiling water nuclear reactors 6!HRs7.the ob&ective of thetechnique is to induce compressive residual stress on the inside surface of the pipe in the weld area bysimultaneously induction heating from the outside while water cooling the inside surface.

PH1$ is to mitigate chloride stress corrosion cracing in austenitic stainless steels. $he I13I technique avoids undesirable metallurgical reactions such as chromium carbide

precipitation and sigma phase formation by inducing compressive residual stresses and utili5ing heatingtemperature and times which do not lead to adverse metallurgical reactions. $he I13I technique to austenitic stainless steel piping is to prevent chloride stress corrosion cracingor other forms of environmental cracing driven by residual stress.

WPS is a written qualified welding procedure prepared to provide direction for maing productionwelds to code requirements. $he purpose for qualification of a HP3 is to determine that the weldment

proposed for construction is capable of providing the required properties for its intended application.HP3 shall be selected on the basis of fabrication code,Pnumber,number,thicness,fillermetal,welding

process, service fluid, minimum design material thicness which is related to impact test. HP3 has three inds of variables. $hat is essential, supplementary and non essential. $he variablewhich will affect the mechanical property of the weldment is the essential variable. $he supplementaryessential variable is required for metals for which other sections specify notchtoughness tests. $he variablewhich does not affect the mechanical properties of the weldment is non essential variable.

Essential )ariables in WPS:

3%AH base metal thicness, weld pass thicness,Pnumber,Po.+B-B*2,'number,Anumber =eposited weld metal thicness, minimum pre heating temperature, type of PH1$, %aximum qualified base metal thicness for PH1$, use of thermal processes. $AH base metal thicness,Pnumber,Po.+B-B*2,'number,Anumber,deletion or addition

9f filler metal, filler metal product form, deposited weld metal thicness, minimum pre 1eating temperature, type of PH1$, maximum qualified base metal thicness for

PH1$, change in shielding gas or K composition of a shielding gas, deletion or"hanges in the nominal composition of the bacing gas, deletion of trailing shieldingas or change in the "omposition of the trailing gas, changes in closed to out chamber,

Gse of thermal process.3AH base metal thicness, weld pass thicness,Pnumber,Po.+B-B*2,'number,Anumber

"hanges in fluxBwire class, changes in alloy flux, addition or deletion or changes in3upplemental filler metal, changes in alloy elements, deposited weld metal thicness,

"hange in flux type, recrushed slag, minimum preheating temperature, type of PH1$, %aximum qualified base metal thicness for PH1$, use of thermal processes.

P-.is a record of welding data used to weld a test coupon.PLR is a record of variables recordedduring the welding of the test coupon. It also contains the test results of the tested specimens. Recordedvariables normally fall within a small range of the actual variables that will be used in production welding.

P/numbers or S/numbersare assigned to the base metals on the basis of composition, weld abilityand mechanical properties to reduce the number of welding procedure qualifications required. $he group


9/31

numbers are assigned additionally to Pnumbers to classify the metals within Pnumbers for the purpose ofprocedure qualification where notchtoughness requirements are specified.

P* to P** steel and steel alloys P0* to P0+ aluminum and aluminum base alloys P* to P+ copper and copper base alloys P/* to P/- nicel and nicel base alloys

P+* to P+ titanium and titanium base alloys P


10/31

LH/20: &oints, LH/2: base metals, LH/2/: filler metals, LH/2+: positions, LH/2


11/31

. %ultiple 6+7 pipe with its axis hori5ontal and with the welding groove in a vertical plane. Helding shall be done without rotating the pipe. /. %ultiple 6


12/31

+ *, , / *, , / all


13/31

=igit 'lux coating type "urrent Arc Penetration Iron powder 2 high cellulose sodium ="@P digging deep 2*2K * high cellulose potassium A"B="@P digging deep 2K 0 high $itania sodium A"B="@ medium medium 2*2K

high $itania potassium A"B=" light light 2*2K / high $itania iron powder A"B=" light light 0+/2K + low hydrogen sodium ="@P medium medium 2K < low hydrogen potassium A"B="@P medium medium 2K 4 iron oxide iron powder A"B=" medium medium +2K ; low hydrogen iron powder A"B="@P medium medium +2K

Purging:

$o give a smooth oxide free penetration bead with good wetting to the parent material.$o provide a better contact angle with parent material which is preferable during service from the view

points of stress reduction and smoother flow within the pipe.@ffectiveness of purging depends upon oxygen content inside the pipe, purge gas containment system, pipediameter, prepurge gas flow rate and prepurge time.%aximum oxygen content shall be not more than *222ppm at the start of welding.Purge gas inlet shall be at a lower level than the bleed hole. !ecause purging gas is denser than air."ard board discs are normally reduced to ash during PH1$ and subsequently washed away.9xygen contents could be measured by using =an sensor 3I analogue sensing device."orrosion resistance of 3.3 weld metals is significantly lower than the parent material.If oxygen content is below *+2 ppm 62.2*+K7, the corrosion resistance of weld metal is similar to that of

parent metal.Adhesive tape is frequently used to seal the root gap and prevent air ingress which is removed progressivelyduring welding.An excessive flow rate will cause internal pressure in the pipe system which may result in a concave rootweld bead profile and possible weld blow out on completion of the &oint.>olume of purging gas should be at least six times the volume of air displaced."onsumable inserts help aligning the pipe ends and automatically set the root gap and reducing root beadcracing due to notch effect.

$o prohibit formation of such "rrich precipitates as chromium carbides this can be done by higher coolingrates associated with purging.Purging gas may again act as a coolant to minimi5e the areas in the 1A? which reach the delta ferriteformation temperatures.'errite promoting elements 6chromium,silicon,molybdenum and columbium7Austenite promoting elements 6nicel, manganese, carbon and nitrogen7@xcessive delta ferrite can adversely affect the material ductility, toughness and corrosion resitance.ferriteseverely causes the embrittleness in the weldment.

%eneral:

(oop file is used to ensure that testing of all the lines present in the unit is done according to thespecifications given in design documents.(oop means hydro testing limit which can be taen from POI= on the basis of pressure, material, service

fluid and continuity.Isoclearance means whether the vents, drains, gaset, stud bolts and valves have been erected as per iso.%echanical clearance means cross verification of piping isometrics and POI=, verifying adequacy andcorrectness of support.1ydro test means completely water filling the lines to be tested and increasing the pressure to *.+ times thedesign pressure of the lowest pressure rated equipment in the loop being tested.1ydro test is required to prove the strength of materials and weld integrity of a system.All expansion &oints, control valves, strainers, orifice plates, inline instruments, P3> are to be isolated fromhydro test loop.!oth water flow O flanged R> direction are same while hydro testing.


14/31

All spring supports are in loced condition.Piping includes designing, fabricating and constructing lines conveying fluids.Pipe line conveys fluid from inlet point of the line to outlet point of the line.$he routing is how the pipe line is developed into space.Isometric drawing is the pictorial view of a three dimensional ob&ect. It is created by angles which are 2degrees from the hori5ontal.

POI= shows all of piping including the physical sequence of branches, reducers, valves, equipment,instrumentation and control valves."ode means a group of general rules or systematic procedures for design fabrication, installation andinspection.3tandard means documentation prepared by a professional, group of committee which contains mandatoryrequirements.$ensile strength means the maximum load applied in breaing a tensile test piece divided by the originalcross sectional area of the test piece.=uctility is a mechanical property used to describe the extent to which materials can be deformed plasticallywithout fracture.'racture toughness is a quantitative way of expressing a materials resistance to brittle fracture when crac is

present.G3: unified numbering system 3'A: specification of filler analysis.="@: straight polarityBnegative polarity. ="@P: reverse polarityBpositive polarity.Alloy steels usually contain *2K total alloy element content, not including " and %n.

0abrication:

P%I shall be done on material to be welded.roove angle and root face shall be checed whether those are up to acceptable limit suggested in fabricationand HP3 as well.It would be better if longitudinal welds are not intersected with circumferential weld.Hhen two different thicnesses of pipes are to be welded, inner diameter shall be matched to get exactalignment by using 2 degree or *:/ taper.'it up shall be done as per I39 by using required number of clamps to avoid distortion.%isalignment shall not exceed the acceptable limit suggested in HP3.Root gap shall be checed whether it is up to acceptable limit suggested in fabrication code and HP3 aswell.

If any angular offset of degree or less fall in fit up, it doesn#t require design consideration as a miter bendas per !*..P%I shall be done after fit up prior to welding.Right electrode shall be selected as per section II part ".P%I shall be done on weld metal after welding.0abrication& assembl( and erection +3,

$he material to be welded is not more than *- mm 6B/in7 in thicness. Post weld heat treatment shall not berequired.'errous metal baing rings shall be of weld able quality. 3ulfur content shall not exceed 2.2+K.Peening is prohibited on the root pass and final pass of a weld.3eal welds shall cover all exposed threads.A fully penetrated groove weld finished with a cover fillet weld having a throat dimension not less than tc

6lesser of 2.4$b or


15/31

Hhen the thicness through weld in any plane through the branch is greater than twice the minimum materialthicness requiring heat treatment, even though the thicness of the components at the &oint is less thanminimum thicness, heat treatment is required.Hhen weld throat thicness is * code, section >, article I $*+2.A designated lot is that quantity of piping to be considered in applying the requirements for examination inthis code.>isual examination shall be performed in accordance with section >,article -%agnetic particle examination of welds shall be performed in accordance with section >, article 4 andappendix , article < andappendix ;.Gltrasonic examination of welds shall be performed in accordance with section >, article / and appendix *0. Radiography of welds shall be performed in accordance with section>, article0 and appendix /. @ach piping system shall be tested to ensure tightness. A preliminary test using air at no more than *42pa 60+psi7 gage pressure may be made prior to

1ydrostatic testing to locate ma&or leas.(ea tests shall be conducted after any heat treatment has been completed.$he final weld connecting piping systems or components which shall be examined either ultrasonically orradio graphically.All &oints, welds and bonds shall be left uninsulated and exposed for examination during lea testing. All

&oints may be primed and painted prior to lea testing unless a sensitive lea test is required.on toxic liquid may be used instead of water. if the liquid is flammable, its flash point shall be at least /-degree.A pressure relief device shall have a set pressure not higher than the test pressure plus the lesser of /+pa6+2psi7 or *2K of the test pressure.1ydrostatic test pressure shall be not less than *.+ times the design pressure. Also test pressure can be taenfrom ($= prior to the hydro test, the system shall be air tested to find out the ma&or leas. $here after thesystem shall be flushed out and air pocets shall be removed by using air valves located at pea point. Afterthat, the system shall be pressuri5ed gradually until *.+ times design pressure is attained and hold the

pressure long enough to equali5e the piping strains.Pneumatic test pressure shall be *.* times design pressure. $he pressure shall be gradually increased until agage pressure which is lesser of one half the test pressure or *42pa 60+psi7 is attained at which time a

preliminary chec shall be made. $here after, the pressure shall be gradually increased in steps until the test

pressure is reached, holding the pressure at each step long enough to equali5e piping strains. $he pressureshall be reduced to the design pressure before examining for leaage.If welds which have not been sub&ected to hydrostatic or pneumatic lea tests, the welds shall beultrasonically or radio graphically examined.Range of pressure gage to be used in hydro test and pneumatic test shall not be greater than *.+ times test

pressure.@lbow can be produced by using bending machine in hot or cold method. After bending has been completed,the elbow shall be heat treated to relieve the residual and thermal stresses.%iter means two or more straight sections of pipe matched and &oined in a plane bisecting the angle of

&unction so as to produce a change in direction.


16/31


17/31

Impact test to determine the amount of impact a specimen will absorb beforefracturing.

$wo types: a. charpy 6beam7 test b. i5od6cantilever7test/. nic#/brea# test to examine the fractured surface for internal defects such as gas pocets, slag inclusions, Porosity, weld ductility, degree of fusion.

+.!ardness test

to determine the resistance to wear of the weld metal. $wo types: a. brinell test b. Rocwell test =epends upon process used, heat input,pre heat or interpass temperature, electrode composition, Plate thicness.etc test macro etch examined by naed eye or by low power magnification up to Q*+ to show cracs, 3lag inclusion, blow holes, shrinage porosity, penetration of weld, boundary between the

Held metal and base metal. %icro etches examined under a microscope at magnifications from Q02 to Q0222."racs and inclusions of microscopic si5e.rain boundaries and solidification structures of weld metal, heat affected 5one and the base metal.=istribution of micro constituents in weld metal.Luality of heat treatment.

P.o* r *O0 preheating temperature *2deg c6($"37 Inter pass temperature 022deg c

>oltage 000;v, "urrent depends on electrode dia. 3hielding gas 6argon7 ;*0(P%

@42*;*, @R 4230@H$h0

P.o* r *O0 preheating temperature *2 deg c6"37 inter pass temperature 0+2 deg c >oltage 000oltage */*;v, current *22*


18/31

P.o.+A r * preheating temperature *;2 deg c Inter pass heating 0+2 deg c Post heating 22 deg c 6minimum 2mts7 3oaing temperature 4*24/+ deg c

%aximum heating rate *22 deg cBhr %aximum cooling rate *22 deg cBhr

1eat input ./< &Bmin @R -23!, travel speed @R -2*;!, travel speed 42 mmBmin 3hielding gas 6argon7 ;*0(P%

P.o.+! r * preheating temperature *;2 deg c+"r 2.+%o Inter pass heating 0+2 deg c Post heating 22 deg c 6minimum 2mts7 3oaing temperature 4*24++ deg c

%aximum heating rate **2 deg cBhr %aximum cooling rate *2 deg cBhr @R ;23!


19/31

P.o.00 preheating temperature *2 deg c Inter pass temperature *4+ deg c @R ++< or @R +++< A" -2*2AB*+02> @H?rB@HP

3hielding, bacing gas 6argon7 ;*0(P%In AC "I% welding&the cleaning of oxide is carried out in the positive half cycleAnd in the negative half, the electrode gets cooled down while the base metal gets heated upaiding adequate fusion in the &oint interface.

P.o./ preheating temperature *2 deg c Inter pass temperature *+2 deg c @R "ui B *;00> 3hielding, bacing gas 6argon7 ;*2(P%

P.o./0 preheating temperature *2 deg c Inter pass temperature *+2 deg c

@ i"u4, 000 @R i"u4, */*;> $ravel speed 4+**2 mmBmin 3hielding gas ;*0(P% !acing gas +;(P%

P.o./ on +A preheating temperature *+2 deg c Post heating temperature 22 deg c 62min7 Inter pass temperature *;2 deg c 3oaing temp. 42/4

@ 0*mn, 020/> 3hielding and bacing gas ;*0(P%


20/31

(iquid penetrant inspection is a non destructive method of revealing the discontinuities thatare open to surface of solid and essentially non porous materials.6imitations: *. =iscontinuities open to surface. 0. 3urface roughness. . ot effective on porous material.Principle:

(P$ depends mainly on penetrant#s wetting property. $he ability of the penetrant to flow over a given surface and enter surface cavities depends on *. "leanliness of the surface. 0. "onfiguration of the cavity. . "leanliness of the cavity. /. 3urface tension of the liquid. $he cohesive forces between molecules of a liquid cause surface tension. +. Ability of the liquid to wet the surface. If the contact angle is less than -2 degree, the liquid is said to have good wetting ability. If the angle is equal to or greater than -2 degree, the wetting ability is considered low.


21/31

Sol)ent remo)able penetrants:that is removed by wiping with clean and lint free material until mosttraces of the penetrant have been removed. $he remaining traces are removed by wiping with clean and lintfree material slightly moistened with solvent.

Penetrant sensiti)it( test:

$he liquid penetrant comparator blocs shall be made of aluminium A3$% ! 02-, type 020/, B; in

6-.+mm7 thic and should have approximate face dimensions of 0 in Q in. At the center of each face 0+mm in diameter shall be mared with +*2 degree " temperature indicating crayon or paint. $he mared areashall be heated with heating device to temperature between +*2 degree and +0/ degree ". the specimenshall be immediately quenched in cold water, which produces a net wor of fine cracs on each face. $he

bloc shall be dried by heating to */- degree ". after cooling8 the bloc shall be cut in half. 9therwise,separate blocs can be used. !ut two comparator blocs with closely matched crac patterns may be used.

Emulsifiers:

@mulsifiers are liquid used to render excess penetrant on the surface of wor piece water washable.*. (ipophilic emulsifiers are oil based. $he emulsifier diffuses into the penetrant film and renders it

spontaneously emulsifiable in water. $he dwell time is in the range of one to four minutes inaccordance with manufacturing recommendations.

0. 1ydrophilic are water based. $hat is diluted in water in concentrations of +K to 2K for dipapplications and 2.2+K to +K for spray applications. It is slower action than the lipophilic emulsifier.$his method requires pre rinse which helps remove the excess penetrant to minimi5e the contaminationof the emulsifier.

De)eloper:

$he purpose of the developer is to increase the brightness of fluorescent indications and contrast ofvisible penetrant indications. $he developer also provides a blotting action, which serves to draw penetrantfrom the flaw to the surface and spreading the penetrant.

Dr( powder de)eloper:

$hat is widely used with fluorescent penetrants. !ut should not be used with visible dye penetrants. !ecause they do not produce satisfactory contrast. Water soluble de)elopers:

It can be used for both penetrants. It is not recommended to use with water washable penetrants.Water suspend able de)eloper:

It can be used with both the penetrants. $hat is supplied as a dry powder which is then dispersed inwater in recommended proportions, usually 2.2/ to 2.*0 NgB(.

1on a2ueous suspend able de)elopers:

It can be used for both the penetrants. $his type of developers is most sensitive form of developersused with fluorescent penetrants.

1ote:*. 3uitable blac light for fluorescent light, that is intensity of blac light shall be minimum of *222HBsq.cm and wave length in the range of 2mm to -2mm.

0. %inimum light intensity at inspection site of 0.+ footcandles 6+2lx7 for visible penetrant. . 1ydrometer is used to measure the specific gravity of water based wet developer.

Acceptance standard:*. Relevant rounded indications shall be less than +mm.0. 'our or more relevant rounded indications in line shall be separated by *.+mm.


22/31

$he magnetic particle examination method may be applied to detect discontinuities on or nearthe surface of ferromagnetic materials.

$he intensity of magneti5ation depends upon the susceptibility of the material to get magneti5ed.*. =iamagnetic metals which have a small and negative susceptibility to get magneti5ed6slightly repelled7

ex: copper, silver and gold

0. Paramagnetic metals which have a small and positive susceptibility to get magneti5ed 6slightly attracted7ex: magnesium, molybdenum, lithium and tantalum.. 'erromagnetic metals which have a large and positive susceptibility to get magneti5ed.6fully attracted7

ex: iron, cobalt and nicel.Principle:

If the discontinuity is open to or close to the surface of magneti5ed material, fluxlines will be distortedat the surface8 it is termed as flux leaage. when fine magnetic particles are distributed over the area of thediscontinuity while the flux leaage exist, magnetic particles will be held in place and the accumulation of

particles will be visible under the proper lighting conditions.Definitions:

%agnetic bar develops the magnetic lines of force which form a closed loop or circuit and generate afield called magnetic field. %agnetic flux is the force that attracts other magneti5able materials to the poles. 'lux density is the flux per unit area through an element which cut the unit area at right angles to thedirection of the flux. Gnit is gauss.

Permeability is the ratio of flux density produced to magneti5ing force. Reluctance is the resistance of a magnetic material to establish magnetic flux. Residual magnetism is the field that remains in ferromagnetic material after the magneti5ing force has

been removed.Retentivity is the ability of a material to retain a portion of the applied magnetic field after the

magneti5ing force has been removed. =emagneti5ation is the reduction of residual magnetism to an acceptable limit. "oercive force is the reverse magneti5ing force necessary to remove the residual magnetism so as todemagneti5e a specimen. 1ysteresis loop is the curve between magneti5ing current and flux density.

A" provides a concentrated flux density near the surface which provides for good detection of surface

discontinuities where as =" provides the best conditions for locating subsurface discontinuities.'etods of magnetization:

*. "ontinuous method in which the current inducing the magnetic flux in the wor piece to beinspected is allowed to flow while the powder is applied. $he induced magnetic field runs in thetransverse direction, producing conditions favorable to the detection of longitudinally disposedcracs.

0. Residual method in which the &ob may be magneti5ed by any method but the magneti5ing source isremoved first and then the magnetic particles are applied over the &ob.

"(pes of magnetization:

*. "ircular magneti5ation will detect discontinuities that are between /+ to -2 degree to the line offorces. A crac that runs parallel to lines of force will not attract particles because no poles or fluxleaage exist at the crac.a. 1ead shot method 6direct induction7

b. Prod method 6direct induction7c. "entral conductor method 6indirect induction70. (ongitudinal magneti5ation in which the lines of force traverse the part in a direction essentially

parallel with its longitudinal axis.a. Joe method : A" electromagnetic yoe shall have a lifting power of at least /.+g

themaximum pole spacing that will be used. =" electromagnetic yoe shallhave a lifting power of at least *;g the maximum pole spacing thatwill be used.


23/31

b. 3olenoid coil method=emagneti5ation is accomplished by sub&ecting the part to a field equal to or greater than that used

to magneti5e the part, then continuously reversing the field direction while gradually decreasing it to 5ero.

AC demagnetization:

Hhen demagneti5ation coil is energi5ed by passing the current through its winding, it induces a

magnetic field on the specimen placed in the coil. Hhen direction of current flow reverses itself, the polarityof the induced magnetic field also reverses with each reversal of the current. $he demagneti5ation isaccomplished only if the specimen is removed from the influence of the demagneti5ation coil while thecurrent is flowing. If the current is stopped while the specimen is still in the magnetic field of influence, itmay still retain some magnetism.DC demagnetization:

$he current is ad&usted to a value at least as great as that initially used to magneti5e the specimen.Hhen direction of current flow reverses itself, the polarity of the induced magnetic field also reverses witheach reversal of the current.

$he magnetic particles generally have high permeability and low retentivity. In wet method, ironoxide powder is used because they are extremely fine and have a lower permeability than the metallic

particles.

1ote:*. Residual field can cause arc blow which affects the molten metal during =" welding operations. 0. Residual field affects painting and plating.

%agnetic particles are usually available in grey, red and blac. $he shape of the magnetic particleshould be spherical and must have a high degree of mobility and still have substantial attractive power. $heround smooth particles offer good mobility but have low attractive power. (ong, slender and &agged particleshave excellent attractive power but do not have mobility to move in the leaage field. =ry magnetic particles are applied by spraying or dusting. Het magnetic particles are applied byflowing, spraying or pouring. =ry powders are usable at temperature of up to


24/31

Principle of .":*. =ifferential absorption 0. Penetration

$he amount of absorption at any point is dependent upon the thicness and density of the matter atthat point. $he depth of penetration is dependent upon the energy of the rays. $hey are electromagnetic with

energy indirectly proportional to their wavelength. $hey have no electrical charge and no mass. $hey travelin straight lines at the velocity of light. $hey can expose film by ioni5ation. $he amount of scatter is directlyproportional to matter density and indirectly proportional to ray energy.

Ad)antages of gamma ra(s:

*. If necessary, a very short source to film distance with a small diameter source can be used.@x: inside the pipe.

0. 3ome ratioisotopes have a very high penetrating power, which maes it possible to obtainsatisfactory radiographs of very thic metal specimens.

Disad)antages of gamma ra(s:

*. 6"o


25/31

+. $ongue is used to handle the source during emergency situation while the source is out of the camera.


26/31

Recommended intensifying screen thicness:

(ocation ofscreen

"o


27/31

$he minimum required thicness of a permanent blan shall be calculated in accordance with this formula as

per !*. tC dgS pB*


28/31


29/31


30/31


31/31

Piping New

Documents