Pipe 41 Contents Pipes and tubes are not the same ..................................................... 42 Welded stainless steel pipe .................................................................. 43 Seamless pipe ............................................................................................ 44 Seamless high temperature stainless steel pipe.......................... 46 High temperature pipe grades and properties .......................... 48 High temperature corrosion properties ........................................ 49 Consider structural stability ................................................................... 49 Recommended operating temperatures in air ........................... 50 Creep rupture strength............................................................................ 50 Pipe specifications and classes.............................................................. 51 Pressure ratings for pipes, tubes and fittings ................................ 52 Stainless steel pressure ratings ............................................................. 53 Basic allowable stress ‘S’ in tension for stainless steels............ 54 Theoretical working pressure for stainless steel seamless pipe .................................................................. 56 Stainless steel welded and seamless pipe - nominal dimensions and weights..................................................... 58 Carbon steel welded and seamless pipe ...................................... 60 Standards - tube, pipe and fittings...................................................... 62 Seamless tube and pipe manufacture .............................................. 64 Welded tube and pipe manufacture................................................. 65 Standards for testing of material ......................................................... 66
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Pipe
41
Contents
Pipes and tubes are not the same ..................................................... 42
Basic allowable stress ‘S’ in tension for stainless steels ............ 54
Theoretical working pressure for stainless steel seamless pipe .................................................................. 56
Stainless steel welded and seamless pipe - nominal dimensions and weights ..................................................... 58
Carbon steel welded and seamless pipe ...................................... 60
Standards - tube, pipe and fittings ...................................................... 62
Seamless tube and pipe manufacture .............................................. 64
Welded tube and pipe manufacture................................................. 65
Standards for testing of material ......................................................... 66
Pipe
42
The terms “pipe”, “tube” and “hollow bar” in common use are often confused. The terminology is used as interchangeable, but in engineering, each relates to specific standards. Pipe and tube are generally produced as either welded (produced from slit coils or from plate), or seamless (hot finished extrusion, or cold finished by pilgering or cold drawing). Hollow bar is produced as a hot extruded (seamless) product, trepanned from round bar, or cast.
Care should be taken when converting between inch size and metric size due to common use of “soft” conversion rather than “hard” conversion e.g. 1” = 25.4 mm (hard conversion), often converted as 25 mm (soft conversion). Using the correct terminology, and specifying the actual dimensions according to the appropriate material “Standard”, will ensure supply of the appropriate product.
A pipe, a tube, or a hollow bar is a term for a long hollow cylinder used mainly to convey substances which can flow, including liquids and gases (fluids), slurries, powders, to machine components, or for structural and architectural applications.
Tube is generally thin wall 0.51 mm to 6 mm thick, specified by the actual OD and WT but may be specified by any two of OD, ID or WT. The term “tube” is also applied to non-cylindrical “hollow sections”, i.e., square (SHS) or rectangular tubing (RHS) and oval - outside dimensions denoted by width and breadth (or height). Refer “Tube introduction” on page 128.
Hollow Bar is generally heavy wall 6 mm to 60 mm thick, specified by OD and ID, but can also be specified as OD and WT. It is an interim “mechanical tube” used for machining components, or further processing into pipe or tube. Refer “Hollow bar” on page 170.
Pipe is generally medium wall 1.65 mm to 12.7 mm. Dimensions as specified by the American National Standards Institute (ANSI) are covered by standards ASME B36.19 for stainless steel and ASME B36.10 for carbon steel. Outside diameter is referenced by the NPS (Nominal Pipe Size - imperial) or DN (Diamètre Nominal - metric) designator, often referred to as the ‘nominal bore’, which has a constant dimension for each given size. Wall thickness is specified in a series of “schedule” numbers i.e. for stainless steel Sch 5S , 10S, 40S and 80S (suffix “S” to differentiate from carbon steel). The “actual” WT for a given schedule number varies as the NB size increases. The “actual” ID varies and is not an exact reflection of the inside bore size. To obtain the actual OD and WT refer to the pipe tables in this section of our catalogue, or the tables in the applicable standards or specifications, e.g. ASME B36.19, ASTM A312 , A358, A790 for stainless steel.
If in doubt, always specify at least 2 dimensions required - O.D. , W.T. or I.D. to ensure correct supply.
Pipes and tubes are not the same
O.D
I.D
w
b
t
W.T.
e..g 100 NB Sch 10S
114.3 mm O.D. x 3.05 mm W.T.114.3 mm O.D. x 108.2 mm I.D.
Welded stainless steel pipe According to ASTM A312M-08a / A999M-04 Austenitic, duplex and superduplex Dimensions acc. to stainless steel Standard ASME B36.19M-2004
Nom Pipe Size Nom ASTM 304L 316L 2205 2507NB / DN NPS Wall O.D. av. wt I.D. Mass UNS S30403 S31603 S31803 S32750mm inch Sch mm mm mm kg/m SANDVIK 3R12 3R65 SAF2205 SAF25078 1/4 Sch 10S 13.72 1.65 10.41 0.5 ● A - - Sch 40S 2.24 9.25 0.6 A A - -10 3/8 Sch 10S 17.15 1.65 13.84 0.6 ● A - - Sch 40S 2.31 12.52 0.8 A A - -15 1/2 Sch 10S 21.34 2.11 17.12 1.0 A A - S Sch 40S 2.77 15.80 1.3 A A S S20 3/4 Sch 10S 26.67 2.11 22.45 1.3 A A S - Sch 40S 2.87 20.93 1.7 A A S S25 1 Sch 10S 33.40 2.77 27.86 2.1 A A S S Sch 40S 3.38 26.64 2.5 A A S S32 1 1/4 Sch 10S 42.16 2.77 36.63 2.7 A A S - Sch 40S 3.56 35.05 3.4 A A S -40 1 1/2 Sch 10S 48.26 2.77 42.72 3.1 A A S S Sch 40S 3.68 40.89 4.1 A A S S50 2 Sch 10S 60.33 2.77 54.79 3.9 A A S S Sch 40S 3.91 52.50 5.4 A A S S65 2 1/2 Sch 10S 73.03 3.05 66.93 5.3 A A - - Sch 40S 5.16 62.71 8.6 A A S -80 3 Sch 10S 88.90 3.05 82.80 6.5 A A S S Sch 40S 5.49 77.93 11.3 A A S S90 3 1/2 Sch 10S 101.60 3.05 95.50 7.4 A A - ●
Sch 40S 5.74 90.12 13.6 A A - ●
100 4 Sch 10S 114.30 3.05 108.20 8.4 A A S S Sch 40S 6.02 102.26 16.1 A A S S125 5 Sch 10S 141.30 3.40 134.49 11.6 A A ● ●
Sch 40S 6.55 128.19 21.8 A A ● ●
150 6 Sch 10S 168.28 3.40 161.47 13.8 A A A ●
Sch 40S 7.11 154.05 28.3 A A S S200 8 Sch 10S 219.08 3.76 211.56 20.0 A A A ●
Sch 40S 8.18 202.72 42.6 A A S A250 10 Sch 10S 273.05 4.19 264.67 27.8 A A A ●
Sch 40S 9.27 254.51 60.3 A A A A300 12 Sch 10S 323.85 4.57 314.71 36.0 A A A ●
Sch 20 * 6.35 311.2 49.71 ● ● ● A Sch 40S 9.53 304.79 73.9 A A ● ●
350 14 Sch 10S 355.6 4.78 346.04 41.4 A A ● ●
Sch 20 * 7.92 339.8 68 ● ● ● A Sch 40S 9.53 337 81.3 A A ● ●
400 16 Sch 10S 406.4 4.78 396.84 47.3 A A ● ●
Sch 40S 9.53 387 93.3 A A ● ●
450 18 Sch 10S 457.2 4.78 447.64 53 A A ● ●
Sch 40S 9.53 438 105 A A ● ●
500 20 Sch 10S 508.0 5.54 496.92 69 A A ● ●
Sch 40S 9.53 540 117 A A ● ●
600 24 Sch 10S 609.6 6.35 596.90 95 A A ● ●
Sch 40S 9.53 591 141 A A ● ●
750 30 Sch 10S 762.0 7.92 746.16 147 ● A ● ●
Sch 40S and Sch 80S above 200 NB are NOT the same as carbon steel Sch 40 and Sch
80 but thinner (equivalent to carbon steel walls STD and X/S above 200NB).
Standard mill lengths 6.1 mtr ≤ 300 NB and 6 mtr > 300 NB.
Other sizes and grades available on enquiry.
Precision cut to length service available.
see page 66 for tolerances.
see page 56 for pressure tables.
Pipe
44
TST-S e.g.TST-S-316L-6-SCH40S
Seamless pipe HF and CF stainless steel pipe acc. to ASTM A312M-08a, A790M-10, ASTM B677, ASTM B668 and A999M-04 Austenitic, superaustenitic, duplex, superduplex Dimensions acc. to stainless steel Standard ASME B36.19M-2004
Sch 40S and Sch 80S above 200 NB are NOT the same as carbon steel
Sch 40 and Sch 80 but thinner (equivalent to carbon steel walls STD and
X/S above 200NB).
Standard mill lengths 5 to 6.7 metre randoms.
Other sizes and grades available on enquiry.
Precision cut to length service available.
see page 56 for pressure tables.
Nom Pipe Size Nom ASTM 304L 316L 2205 2507 2707 HD 904L –NB / DN NPS Wall O.D. av. wt I.D. Mass UNS S30403 S31603 S31803 S32750 S32707 N08904 N08028mm inch Sch mm mm mm kg/m SANDVIK 3R12 3R65 SAF2205 SAF2507 SAF 2707
HD2RK65 Sanicro
286 1/8 Sch 10S 10.29 – – – – – – – – – – Sch 40S 1.73 6.83 0.4 – A – – – – – Sch 80S 2.41 5.46 0.5 – A – – – – –8 1/4 Sch 10S 13.72 1.65 10.41 0.5 ● A – – – – – Sch 40S 2.24 9.25 0.6 A A – – – – – Sch 80S 3.02 7.67 0.8 ● A – – – – –10 3/8 Sch 10S 17.15 1.65 13.84 0.6 A A – – – – – Sch 40S 2.31 12.52 0.8 A A – – – – – Sch 80S 3.20 10.74 1.1 A A – – – – –15 1/2 Sch 10S 21.34 2.11 17.12 1.0 ● A A – – ● Sch 40S 2.77 15.80 1.3 A A A A – A** ● Sch 80S 3.73 13.87 1.6 A A A A – A** Sch 160 4.78 11.8 2.0 – A – – – – 20 3/4 Sch 10S 26.67 2.11 22.45 1.3 A A A – – – Sch 40S 2.87 20.93 1.7 A A A – – ●** ● Sch 80S 3.91 18.85 2.2 A A ● A – A** Sch 160 5.56 15.5 2.9 – A – – – – 25 1 Sch 10S 33.40 2.77 27.86 2.1 A A A – – – ● Sch 40S 3.38 26.64 2.5 A A A A – ●** ● Sch 80S 4.55 24.31 3.2 A A A A – A** Sch 160 6.35 20.7 4.2 A A – A – – 32 1 1/4 Sch 10S 42.16 2.77 36.63 2.7 A A A – – Sch 40S 3.56 35.05 3.4 A A A ● – ●** Sch 80S 4.85 32.46 4.5 ● A – – – ●** Sch 160 6.35 29.5 5.6 A A – – – – 40 1 1/2 Sch 10S 48.26 2.77 42.72 3.1 A A A S – – Sch 40S 3.68 40.89 4.1 A A A A – ● ● Sch 80S 5.08 38.10 5.4 A A A A – A Sch 160 7.14 34.0 7.3 – A – A – 50 2 Sch 10S 60.33 2.77 54.79 3.9 A A A – – ● Sch 40S 3.91 52.50 5.4 A A A A A ● ● Sch 80S 5.54 49.25 7.5 A A A A – A Sch 160 8.74 42.8 11.1 ● A – A – ● 65 2 1/2 Sch 10S 73.03 3.05 66.93 5.3 A A A – – – Sch 40S 5.16 62.71 8.6 A A A – – ● Sch 80S 7.01 59.00 11.4 ● A ● – – ● Sch 160 9.53 54.0 14.9 – A – – – – 80 3 Sch 10S 88.90 3.05 82.80 6.5 A A A – – – ● Sch 40S 5.49 77.93 11.3 A A A A A ● ● Sch 80S 7.62 73.66 15.3 A A A A – A Sch 160 11.13 66.6 21.4 ● A – – – – 90 3 1/2 Sch 10S 101.60 3.05 95.50 7.4 ● A – – – – Sch 40S 5.74 90.12 13.6 ● ● – – – – Sch 80S 8.08 85.45 18.6 ● A – – – – Sch 160 – – – – – – – – – –
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Tolerances StandardsSandvik 3R12 (ASTM 304L), 3R65 (ASTM 316L), 6R35 (ASTM 321)ASTM A312 incl. corrosion test acc. to ASTM A262 Pr.E.NACE MRO175 / ISO 15156-1:2001(3R12, 3R65) NFA 49-117, tolerances and leak test acc. to ASTM A312/A999
Sandvik SAF 2205 (UNS S32205, S31803) and SAF 2507 (UNS S32750)ASTM A790 incl. corrosion test acc. to ASTM G-48 Method A(SAF 2205 at 25°C, SAF 2507 at 50°C, both for 24 h)
Sandvik 2RK65 (UNS N08904)ASTM A312Sizes marked ** are also tested acc. to AD2000-W2 Einbaurohre TüV Bl. 421 incl. hot tensile test at +400°C
Sandvik Sanicro 28 (UNS N08028)ASTM B668 average wall
TST-S e.g.TST-S-316L-6-SCH40S
Seamless pipe HF and CF stainless steel pipe acc. to ASTM A312M-08a, A790M-10, ASTM B677, ASTM B668 and A999M-04 Austenitic, superaustenitic, duplex, superduplex Dimensions acc. to stainless steel Standard ASME B36.19M-2004
Size O.D. tol W.T. tol % Thk/ODmm mm av. wall ratio
10-48.3 + 0.4 / -0.8 + 20 / -12.5 all
> 48.3 - 73.02 + 0.4 / -0.8 + 20 / -12.5 all
> 73.02 - 114.3 + 0.8 / -0.8 + 22 / -12.5 ≤ 5%
> 114.3 - 219.1 + 1.6 / -0.8 + 22 / -12.5 ≤ 5%
Note: WT tol > 88.9 - 219.1 + 22 / -12.5 > 5%
Size O.D. tol. Wall thickness tol.mm mm av wall % min wall %
16 - 48.26 ± 0.19 ± 10 + 20 / -0
> 48.26 - 88.9 ± 0.25 ± 10 + 22 / -0
> 88.99 - 114.0 ± 0.38 ± 10 + 22 / -0
> 114.0 ± 0.51 ±10 + 22 / -0
Valid for 2RK65 According to ASTM A312-08a Valid for Sanicro 28 According to ASTM B-668 (B-829)Pipe is stocked with average wall
Nom Pipe Size Nom ASTM 304L 316L 2205 2507 2707 HD 904L –NB / DN NPS Wall O.D. av. wt I.D. Mass UNS S30403 S31603 S31803 S32750 S32707 N08904 N08028mm inch Sch mm mm mm kg/m SANDVIK 3R12 3R65 SAF2205 SAF2507 SAF
2707 HD2RK65 Sanicro
28100 4 Sch 10S 114.30 3.05 108.20 8.4 A A A – – – Sch 40S 6.02 102.26 16.1 A A A A A – Sch 80S 8.56 97.18 22.3 A A A A – A Sch 160 13.49 87.3 33.5 ● ● – – – – 125 5 Sch 10S 141.30 3.40 134.49 11.6 A A – – – – Sch 40S 6.55 128.19 21.8 ● A – – – – Sch 80S 9.53 122.25 31.0 ● A – – – – Sch 160 15.88 109.6 49.1 ● ● – – – – 150 6 Sch 10S 168.28 3.40 161.47 13.8 A A – – – – Sch 40S 7.11 154.05 28.3 A A A – – – Sch 80S 10.97 146.33 42.6 A A – A – – Sch 160 18.26 131.7 67.6 ● ● – – – – 200 8 Sch 10S 219.08 3.76 211.56 20.0 A A – – – – Sch 40S 8.18 202.72 42.6 A A A – – – Sch 80S 12.70 193.68 64.6 A A – A – – Sch 160 23.01 173.1 111.3 ● ● – – – – 250 10 Sch 10S 273.05 4.19 264.67 27.8 A A – – – – Sch 40S 9.27 254.51 60.3 ● A – – – – Sch 80S 12.70 247.65 81.6 ● A – – – – 300 12 Sch 10S 323.85 4.57 314.71 36.0 ● A – – – – Sch 40S 9.53 304.79 73.9 ● A – – – – Sch 80S 12.70 298.45 97.5 ● A – – – –
For ASTM A312 and ASTM A790, acc. to ASTM A999Valid for all grades except 2RK65 and Sanicro 28
Pipe
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Seamless high temperature stainless steel pipeHigh temperature grades HF and CF stainless steel pipe according to ASTM A312M-08a, A268M-10, ASTM B407, A999M-04 and EN ISO 1127
** Not applicable for tube and pipe. Only for information.
Sandvik, Sanicro and Kanthal are trademarks owned by Sandvik AB.
253 MA and 353 MA are trademarks owned by Outokumpu Stainless.
What are “H” grades “H” grades are the higher carbon versions of the standard or low carbon grades, produced primarily in plate, bar, pipe and tube. The high carbon content (0.04% C min. - 0.10%) results in increased strength of the steel at elevated temperatures (generally above 500°C), with higher tensile strength (short term) and “creep” strength (long term). These grades are susceptible to “sensitisation” due to the formation of chromium carbides at the grain boundaries if held in the temperature range of about 450-850°C which can lead to intergranular corrosion when operating in aqueous environments such as during shutdown and below dewpoint of the gas.
Commonly requested grades are 304H and 316H, for which there is a slightly different chromium content range (0.5%) to the standard grade 304 and 316. In addition all austenitic “H” grades must have a grain size of ASTM No 7 or coarser. Other high temperature grades are “stabilised” by addition of titanium (eg 321 or 316Ti) or niobium (eg 347) and therefore do not suffer from sensitisation even after exposure at 450°C – 850°C because the Ti or Nb combines preferentially with the carbon, leaving the chromium free to provide resistance to corrosion.
The pressure vessel codes give the same allowable pressure rating for “H” grades as for standard grades
- the “H” grades are simply the standard grades with their carbon contents controlled to the top half of the range, or slightly above. Standard grades can often be used in place of “H” grades so long as their chemical composition (carbon and chromium) mechanical properties (tensile and yield strength), and grain size meet the “H” limits. The grain size requirement may be satisfied by extra testing. The product and its test certificate may describe it as a standard 304 or 316 unless it was originally manufactured as a “H” grade. If an application requires an “H” grade - generally for high temperature applications - this must be specified at time of order. Full compliance with “H” grade specification may require additional measurement of grain size. Due to availability issues, it is sometimes desirable to be able to use a product labelled as a standard grade when an “H” grade has been specified. Mills’ inspection certificates give this information. Such substitution can be made where standard grades can be used as “H” grades so long as the chemical and mechanical properties and grain size conform to the “H” grade requirements. Full details given on the mill inspection certificate will show whether the standard grade meets compliance with the “H” grade chemical and mechanical requirements, while additional testing will most likely be required to confirm grain size.
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High temperature corrosion properties
Consider structural stability
Almost all steels developed to combat corrosive environments at elevated temperatures can suffer from embrittlement due to a secondary phase formation. A common type is sigma-phase, which is formed after a longer period of service in the temperature range 600 to 850°C.
The amount of sigma-phase formed is related to the chemical composition of the material. Chromium rich materials are, in general, more prone to form a sigma-phase. On the other hand, elements like nickel and nitrogen hinder the formation of sigma-phase. Nitrogen is a very efficient sigma-phase blocker, which is why Sandvik 253 MA is less prone to sigma-phase formation in comparison to some of the more common high temperature grades such as ASTM 309 and ASTM 310H – due to its unique chemical content (slightly lower chromium and lower nickel). Ferritic steels with more than 16% chromium are very sensitive to sigma-phase formation. Ferritic chromium steels are also prone to embrittlement in the temperature range 400 to 550°C (475°C - embrittlement). Heat treatment at 1,000 to 1,100°C dissolves most embrittling phases and returns the material to a ductile state.
A comparison between Sandvik high temperature materials and ASTM 304H
Grade In air Oxidizing sulfur Reducing sulfur Carburizing Nitriding
ASTM Sandvik
304H 5R10 0 0 0 0 0
321H 6R35 0 0 0 0 0
347H 8R40 0 0 0 0 0
316H 6LR62 0 0 0 0 0
309 8RE18 ++ ++ + + ++ (**)
310H* 7RE10 +++ ++ 0 ++ ++
– Sandvik 253 MA* ++++ +++ ++ +++ ++ (**)
– Sandvik 353 MA* ++++ + 0 ++++ ++++
– Sandvik Sanicro 31HT* ++ + 0 +++ +++
Alloy Sandvik Sanicro 61 ++++ 0 - + ++
Alloy Sandvik Sanicro 70 +++ 0 - + ++++
446-1 Sandvik 4C54* ++++ +++ ++++ - -
446-2 Sandvik 2C48 +++ +++ +++ - -
– Kanthal APM +++++ ++++ ++++ ++++ +++(***)
– Kanthal APMT +++++ ++++ ++++ ++++ +++(***)
* Sandvik stock standard
** In low oxygen potential (<100ppm O2) nitriding may occur
*** In low dew point (<-20°C) severe nitriding may occur
0 = reference value + = superior to - = inferior to
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Recommended operating temperatures in air
Creep rupture strength
Material
Sandvik ASTM
5R10 304H
6R35 321H
8R40 347H
6LR62 316H
8RE18 309
7RE10 310H
253 MA –
353 MA –
Sanicro 31HT –
Sanicro 61 Alloy
Sanicro 70 Alloy
4C54 446-1
2C48 446-2
Kanthal APM –
–Kanthal APMT
Pipe
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The term pipe covers a specific range of sizes laid down by ANSI specifications. Any sizes not covered by these specifications are tube. Stainless Steel Pipe dimensions determined by ASME B36.19 covering the outside diameter and the Schedule wall thickness. Note that stainless wall thicknesses to ANSI B36.19 all have an ‘S’ suffix. Sizes without an ‘S’ suffix are to ANSI B36.10 which is intended for carbon steel pipes.
Pipe specifications and classes
Seamless and WeldedASTM A312: Seamless and straight-seam welded austenitic pipe intended for high temperature and general corrosive service. Filler metal not permitted during welding.
ASTM A358: Electric fusion welded austenitic pipe for corrosive and/or high temperature service. Typically only pipe up to 8 inch is produced to this specification. Addition of filler metal is permitted during welding.
ASTM A790: Seamless and straight-seam welded ferritic/austenitic (duplex) pipe intended for general corrosive service, with a particular emphasis on resistance to stress corrosion cracking.
ASTM A409: Straight-seam or spiral-seam electric fusion welded large diameter austenitic light-wall pipe in sizes 14” to 30” with walls Sch 5S and Sch 10S for corrosive and/or high temperature service.
ASTM A376: Seamless austenitic pipe for high temperature applications.
ASTM A813: Single-seam, single or double-welded austenitic pipe for high temperature and general corrosive application.
ASTM A814: Cold-worked welded austenitic pipe for high temperature and general corrosive service.
Note: Welded pipes manufactured to ASTM A312, A790 and A813 must be produced by an automatic process with NO addition of filler metal during the welding operation.
Welded Pipe SpecificationsUsually it will be to ASTM A312. If it is to ASTM A358 then there are various Classes available as shown below. The Class Number dictates how the pipe is welded and what non-destructive tests:
Class 1: Pipe shall be double welded by processes employing filler metal in all passes and shall be completely radiographed.
Class 2: Pipe shall be double welded by processes employing filler metal in all passes. No radiography is required.
Class 3: Pipe shall be welded in one pass by processes employing filler metal and shall be completely radiographed.
Class 4: Same as Class 3 except that the welding process exposed to the inside pipe surface may be made without the addition of filler metal.
Class 5: Pipe shall be double welded by processes employing filler metal in all passes and shall be spot radiographed.
Markings on pipeThe full identification of the pipe should be continuously marked down its whole length, including:
• Nominal Pipe Size (Nominal Bore)
• Schedule (Wall Thickness)
• Specification
• Grade
• Method of Manufacture (Seamless or Welded)
• Heat Number
• Manufacturer’s Name or Symbol
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52
Pressure ratings for pipes, tubes and fittings
Wall thickness calculations for straight pipe under internal pressureThe following equations and tables are based on those provided in the Process Piping Specification, ASME 31.3a-1996, ASME Code for Pressure Piping (see Notes for references to source paragraphs and tables in this specification).
Firstly, anyone of the following four equations may be used to calculate the ‘pressure design wall thickness’ (t) of a straight pipe subject to internal pressure.
The equations assume t < D/6 (for pipe with t ≥ D/6 or P/SE > 0.385 additional factors need to be considered).
The four alternative equations are:
Where:
t = Pressure design thickness
d = Inside diameter of pipe. For pressure design calculation, the inside diameter of the pipe is the maximum value allowable under the purchase specification
P = Internal design pressure
D = Outside diameter pipe as listed in tables of standards or specifications or as measured
E = Quality factor. See the table “Basic quality factors ‘E’ for longi-tudinal weld joints in stainless steel pipes, tubes and fittings” on page 53
S = Stress value for material from the table “Basic allowable stresses ’S’ in tension for stainless steels” on page 54
Y = Coefficient from table “Values of coefficient ‘Y’ for t<O/S” on page 53
t = PD2(SE + PY)
t = PD2SE
t = D2
SE - PSE + P
1 -
t = P(d + 2c)2[SE - P(1 - Y)]
Secondly, the minimum required wall thickness tm of straight sections of pipe is determined in accordance with the following equation.
where:
tm = Minimum required thickness, including mechanical, corrosion-and erosion allowances
c = The sum of the mechanical allowances (thread or groove depth) plus corrosion and erosion allowances. For threaded components, the nominal thread depth (dimension h of ASME B1.20.1, or equivalent) shall apply. For machined surfaces or grooves where the tolerance is not specified, the tolerance shall be assumed to be 0.5 mm (0.02 in) in addition to the specified depth of the cut.
The actual minimum thickness for the pipe selected, considering manufacturer’s tolerance, shall not be less than tm
Units of Measure for CalculationsIt is important to use compatible units for pressure calculations. ASTM and ASME/ANSI specifications are based upon imperial sizes.
Pipe bendsThe equations above may also be used for pipe bends provided the requirement for minimum wall thickness (tm) is met.
tm = t + c
Worked Example:Taking the simplest equation: t = PD
2SE
A. If you wish to calculate what wall thickness should be used in a design for the following situation:P = Internal Design Pressure – For this example lets say 2000 pounds
per square inch = 2ksi
D = Outside Diameter – For this example lets say 4 inch nominal bore = 4.5 inches
S = Stress Value for material from table below taking into account operating temperature – For
this example lets take ASTM A312 TP 316L operating at 500OC for which S = 14.4 ksi (1ksi = 1,000 psi / psi = Pounds Pressure per Square Inch)
E = Quality Factor from table below according to manufacturing-specification – For this example we are using ASTM A312 TP 316L Seamless for which E = 1.0
So this gives: t = 2 x 4.5 = 0.313 inches
2 x 14.4 x 1.0
Thus we would use 4 inch Nominal Bore Schedule 80S which has a wall thickness of 0.337 inches. If the wall thickness calculation leads to a heavier wall than is available then the pipe diameter must be increased. Depending upon the design of the system this may also reduce the pressure.
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53
Stainless steel pressure ratings
Values of coefficient ‘Y’ for t<D/STemperature, °F (°C)
– The above table and the equations are based on paragraph 304.1 of ASME B31.3a-1996
– The value for Y may be interpolated for intermediate temperatures. For t > D/6:
Y = d + 2cD + d + 2c
Basic quality factors ‘E’ for longitudinal weld joints in stainless steel pipes, tubes and fittingsSpecification No. Class (or Type) Description E Notes
A 182 – Forgings and Fittings 1.00 –
A268
– Seamless Tube 1.00 –
– Electric Fusion Welded Tube, Double Butt Seam 0.85 –
– Electric Fusion Welded Tube, Single Butt Seam 0.80 –
A269
– Seamless Tube 1.00 –
– Electric Fusion Welded Tube, Double Butt Seam 0.85 –
– Electric Fusion Welded Tube, Single Butt Seam 0.80 –
A312
– Seamless Pipe 1.00 –
– Electric Fusion Welded Pipe, Double Butt Seam 0.85 –
– Electric Fusion Welded Pipe, Single Butt Seam 0.80 –
– Electric Fusion Welded Pipe, Single Butt Seam 0.80 –
A430 – Seamless Pipe 1.00 –
A 789
– Seamless 1.00 –
– Electric Fusion Welded Pipe, 100% radiographed 1.00 –
– Electric Fusion Welded Tube, Double Butt Seam 0.85 –
– Electric Fusion Welded Tube, Single Butt Seam 0.80 –
A 790
– Seamless 1.00 –
– Electric Fusion Welded Pipe, 100% radiographed 1.00 –
– Electric Fusion Welded Pipe, Double Butt Seam 0.85 –
– Electric Fusion Welded Pipe, Single Butt Seam 0.80 –
Note:
– This table is based on Table A-1B of ASME B31.3a-1996
1. An E factor of 1 .00 may be applied only if all welds, including welds in the base material, have passed 100% radiographic examination. Substitution of ultrasonic examination for radiography is not permitted for the purpose of obtaining an E of 1.00.
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Basic allowable stress ‘S’ in tension for stainless steelsASTM Spec No.
Notes- This table is based on Table A-1A of ASME B31.3a-1996.- For specified minimum tensile and yield strengths refer to the individual ASTM specifications in Sections 2 and 3.- Minimum temperatures in °C: -20 °F = -29 °C, -60 °F = -51 °C, -325 °F = -199 °C, -425 °F = -254 °C1 For temperatures above 538 °C (1000 °F), these stress values may be used only if the material has been heat treated at a temperature of
1093°C (2000°F) minimum.2 When the material has not been solution heat treated, the minimum temperature shall be -29 °C (-20 °F) unless the material is impact tested.3 Must be verified by tensile test.4 For temperatures above 538 °C (1000 °F), these stress values apply only when the carbon content is 0.04% or higher.5 For temperatures above 538 °C (1000 °F), these stress values may be used only if the material has been heat treated by heating to a minimum
temperature of 1038 °C (1900 °F) and quenching in water or rapidly cooling by other means.6 This steel is intended for use at high temperatures; it may have low ductility and/or low impact properties at room temperature after being used
at higher temperatures.7 If the chemical composition of this Grade is such as to render it hardenable, qualification under P-No. 6 is required.8 Increasingly tends to precipitate intergranular carbides as the carbon content increases above 0.03%.9 This steel may develop embrittlement after service at approximately 316 °C (600 °F) and higher temperature.10 This material when used below -29 °C (-20 °F) shall be impact tested if the carbon content is above 0.10%.11 The stress values above 538 °C (1000 °F) shall be used only when the micrograin size, is No. 6 or less (coarser grain). Otherwise, the lower
stress values listed for the same material, specification, and grade shall be used.
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Theoretical working pressure for stainless steel seamless pipe
The information presented above are typical or average values and are not a guarantee of maximum or minimum values.
Conversion factors 1 MPa = 1 N/mm2
1 MPa = 145.04 psi
1 psi = 0.007 MPa
1 Kg f/mm2 = 9.807 MPa
1 Kg f/mm2 = 1422.34 psi
1 bar = 14.5 psi
1 bar = 0.1 MPa
1 MPa = 1000 KPa
Welded pipe: use joint factor 0.85
Pipe schedules
NB NPS 5S 10S 40 40S / STD 80 80S / XS 160 XXS
mm inch
6 1/8 3241 4537 6296 6296 8796 8796
8 1/4 3403 4514 6111 6111 8264 8264
10 3/8 2722 3611 5056 5056 7000 7000
15 1/2 2902 3705 4866 4866 6563 6563 8393 13125
20 3/4 2322 2964 4036 4036 5500 5500 7821 11000
25 1 1854 3108 3793 3793 5105 5105 7129 10209
32 1.1/4 1468 2462 3163 3163 4315 4315 5648 8630
40 1.1/2 1283 2151 2862 2862 3947 3947 5546 7895
50 2 1026 1721 2432 2432 3442 3442 5432 6884
65 2.1/2 1083 1565 2648 2648 3600 3600 4891 7200
80 3 889 1286 2314 2314 3214 3214 4693 6429
90 3.1/2 778 1125 2119 2119 2981 2981 5963
100 4 692 1000 1975 1975 2808 2808 4425 5617
125 5 735 903 1739 1739 2528 2528 4213 5056
150 6 617 759 1585 1585 2445 2445 4070 4891
200 8 474 644 1400 1400 2174 2174 3939 3804
250 10 467 576 1273 1273 2072 1744 3924
300 12 459 529 1194 1103 2024 1471 3859 2941
350 14 418 504 1173 1004 2009 1339 3766
400 16 387 441 1172 879 1978 1172 3736
450 18 344 392 1171 781 1952 1042 3710
500 20 353 409 1114 703 1933 938 3692
600 24 341 391 1075 586 1905 781 3663
Working pressures for ASTM 304 and 316 pipe to ASTM A312 between - 20°F and 100°F.
The ASME code suggests a safety factor of four based on burst pressure.
e.g. - 1” SCH40 = 3793PSI (15171 ÷ 4)
For higher temperatures multiply working pressure by: (according to ANSI B31.3)
40°C 150°C 260°C 540°C
ASTM 304 1.000 1.000 0.875 0.715
ASTM 316 1.000 1.000 0.895 0.765
SAF 2304 1.445 1.350 1.260
SAF 2205 1.500 1.445 1.360
SAF 2507 1.935 1.655 1.570
Pressures in psi
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Theoretical bursting pressure for stainless steel seamless pipe
Pressure pipeDuplex pipe can replace 304 or 316 pipe:
Sch 10S duplex can replace Sch 40S to 50 NB
Sch 40S duplex can replace Sch 80S to 100 NB
Pressures in psi
Bursting pressures
P = 2 x S x t
D
P = Pressure Rating (psi or MPa)
S = Minimum Tensile Strength (psi or MPa)
t = Wall Thickness (inch or mm)
D = Outside Diameter (inch or mm)
The information presented above are typical or average values and are not a guarantee of maximum or minimum values.
ASTM 304 and 316 pipe to ASTM A312 based on 75,000 psi Tensile Strength
Stainless steel welded and seamless pipe - nominal dimensions and weightsNominal wall thickness, minimum and maximum allowable wall thickness according ASTM A312M-10 table 3
Stainless steel thickness are specifed as Sch “..S” numbers and above 200 NB are NOT the same as corresponding “Sch” carbon steel thicknesses. Carbon steel dimensions are specified in ASME B36.10M-04 to 2000mm (80 “) N.B. with w.t. Sch 10 to Sch XXS (double extra strong).
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O.D. and wall thickness tolerancesPermissable Variations in Outside Diameter and Wall Thickness According to ASTM A312M-10 table 3, and ASTM A999M-04a table 1
O.D. W.T. NPS Designator Over Under Tolerance from Nominal Weight
mm mm Over % Under %
6 mm - 40 mm incl. 0.4 0.8 20 12.50
Over 40mm - 65 mm incl. 0.8 0.8 20 12.50
Over 65mm - 100 mm incl. 0.8 0.8 20 12.50
Over 100mm - 200 mm incl. 1.6 0.8 20 12.50
Over 200mm - 450 mm incl. 2.4 0.8 20 12.50
Over 450mm - 650 mm incl. 3.2 0.8 20 12.50
Over 650mm - 850 mm incl. 4.0 0.8 20 12.50
Over 850mm - 1200 mm incl. 4.8 0.8 20 12.50
Stainless Steel and Carbon Steel wall thickness designation comparisonLike schedule numbers with same nominal wall thickness Size range inclusive
Sch 10S & Sch 10 same wall thickness to 200 NB
Sch 40S , Sch 40 and Standard Weight (STD ) same wall thickness to 250 NB
Sch 80S , Sch 80 and Extra Strong (XS) same wall thickness to 200 NB
Sch 80S and Extra Strong (XS) same wall thickness to 600 NB
Sch 160 and Sch 160 (SS sizes based carbon steel standard) same wall thickness, limited avail in SS
Double Extra Strong (XXS) carbon steel only
Non standard sizes of stainless steel pipe can be produced in seamless or welded for most carbon steel dimensions, subject to minimum quantities, and production lead times.
Stainless steel welded and seamless pipe - tolerances
Surface finishSurface imperfections such as handling marks, straightening marks, mandrel and die marks, shallow surface pits, or scale pattern are not considered defects if they are removable within the wall thickness tolerance or 0.1 mm, whichever is greater.
See page 269.
Dimensions and weightsMetric sizes based on 1 in. = 25.4mm Weights based steel plain end pipe 1 lb/ft = 1.4895 kg/m
Weight calculation formula: Wpe = weight to nearest 0.01kg in kg/mD = specified O.D. to nearest 0.1mm up to 406.4 mm
and to nearest 1.0 mm for larger sizes.t = specified wall thickness to the nearest 0.01 mm
Min. wall calculation formula: tn x 0.875 = tmtn = nominal (average) wall in mm rounded to 1
decimal placetm = min. wall in mm rounded to 1 decimal place
Straightness tolerance - ASTM A999M-04a section 161. All - the finished pipe shall be reasonably straight
2. For metal-arc welded pipe, the maximum deviation shall be 3.2 mm measured from a 3 m straight edge, where both ends are in contact with the pipe
OvalityIncluded in the tolerances for specified O.D. except thin wall pipes (wt 3% or less of O.D.) where ovality is not to exceed 1.5% of the specfied O.D.
Welded pipe - specified single and double weldsWelded pipe ≤ 350 NB shall have a single longitudinal weld.
Welded pipe > 350 NB shall have a single longitudinal weld OR two longitudinal welds where formed from plate.
Note: The weld area for sizes ≥ 350 NB can be higher than the surface on the O.D. & I.D. subject to depth of the weld. This may affect surface finish and roundness, particulary on pipe with 2 welds. Forming from plate, the weld area can be fairly wide and flat, generally not suitable for decorative or close fit uses.
NB NPS O.D. av w.t I.D. av w.t I.D. av w.t I.D. av w.t I.D. av w.t I.D. av w.t I.D. mm inch mm mm mm kg/m mm mm kg/m mm mm kg/m mm mm kg/m mm mm kg/m mm mm kg/m
Carbon steel welded and seamless pipe Seamless and welded carbon steel pipe acc. to ASTM specifications, e.g. ASTM A106, ASTM A53, API 5L line pipe
Nominal dimensions and weights acc. to carbon steel Standard ASME B36.10M-04(Theoretical ID included for reference - all dimensions are subject to tolerances nominated in relevant specifications)
av w.t. = average wall thickness= Equivalent stainless steel dimensions for quick comparison to carbon steel sizes
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= Equivalent stainless steel dimensions for quick comparison to carbon steel sizes
*ASME B36.10M-04 does not include Sch 160 or XXS wall thickness for 6 NB, 8 NB and 10 NB. For reference these non standard thicknesses are listed acc. to Forged Fitting Standard ASME B16.11-09 Table 8
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Standards - tube, pipe and fittings
Standards make it possible for designers to easily specify a well-defined material for a given application – chemical composition, size, properties, etc. The standards define the production route, what tests shall be performed, how the testing shall be carried out and how the results shall be reported.
A brief description of common standards is given below.
ASME American Society of Mechanical Engineers
ASTM American Society for Testing and Materials
MSS Manufacturer’s Standardisation Society
NACE National Association of Chemical Engineers (The Corrosion Society)
ISO International Organisation for Standardisation
EN Europäische Norm, i.e. European standard
DIN Deutsches Institut für Normung
PED Pressure Equipment Directive
VdTüV Vereinigung der Technischen Ueberwachungsvereine
BS British Standard
UNS Unified Numbering System
AS Australian Standard
ASMEB16.47 Large diameter flanges 26” to 60” NB
B16.5 Pipe flanges and flanged fittings as per ASTM
B16.9 Factory-made wrought buttwelding fittings as per ASTM such as 90 / 180 deg long radius and short radius elbows tees, crosses, reducing fittings, caps and stub ends short length
B16.11 Forged fittings, socket-welding and threaded as per ASTM
B16.25 Buttwelding ends
B16.28 Wrought steel buttwelding short radius elbows and returns as per ASTM
B36.10 Welded and seamless wrought steel pipe
B36.19 Stainless steel pipe
ASTM/ASMEA182 Stainless steel forged flanges, fittings and
valves
A213 Seamless ferritic and austentitic alloy steel boiler, superheater and heat exchanger tubes.
A249 Welded austenitic steel boiler, superheater, and heat exchanger tubes
Sheet or plate Forming into slotted tubes Welding Grinding
Cutting Calibration Pickling Inspection and stenciling
Heat treatment CalibrationPickling Straightening
Cutting Hydrostatic testing PicklingRadiography Inspection and stenciling
Welded tube and pipe manufacture
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Standards for testing of material
Seamless tube, pipe and hollow bar Steel grade Sandvik / ASTM TP / UNS
Tube and pipe 3R12 3R60 6R35 5R75 SAF 2205 SAF 2507 304L 316L 321 S31803 S32750
Hydraulic tubing
InstrumentationtubeImperial sizes
Sizes acc. toANSI B36.19
Metric sizes
Hollow bar
Steel grade Sandvik / TP / UNS
Tube and pipe 2RK65 Sanicro 28 4C54 7RE10 253 MA 353 MA Sanicro 31HT N08904 N08028 446-1 S31008/S31009 S30815 S35315 N08811/N08810
InstrumentationtubeImperial sizes
Sizes acc. to
ANSI B36.19
Tube and pipefor high temperatures
SS 219711 1) ASTMDIN 17458 10) A213-AW,
TC1 A269NFA 49–117 A632
PED 97/23/EC EN10216-5 TC1
ASTM A269PED 97/23/ECEN10216-5 TC1
ASTM B668PED 97/23/ECEN10216-5 TC1
ASTM B668
ASTM, A213-AWA269A632PED 97/23/EC EN10216-5 TC1
ASTM A312
3R65 2)
ASTM A312 3)
NFA 49-117 4)
ASTM A268 ASTM A312,DIN17458, PK 1NFA 49-117
ASTM A312 ASTM A312 ASTM B407 8)
SS 2197111)
DIN 17458 10)
TC1NFA 49 -117PED 97/23/EC EN10216-5 TC1
Sanmac 304LSanmac 316LData sheet 5)
NFA 49-317 12)
DIN 17456, DIN 17458 PK1 6)
PED 97/23/EC EN10216-5 TC1 6)
DIN 17458 10)
TC1PED 97/23/EC EN10216-5 TC1
ASTM A312 3) ASTM A790 11)
DIN 17458, TC1 10)PED 97/23/EC EN10216-5 TC1
AD-W2, DIN 17458PED 97/23/EC EN10216-5 TC1
Sanmac 4571DIN 17456 6)
Data sheet 5)
PED 97/23/ECEN10216-5TC16)
Sanmac SAF 2205Data sheet13)
PED 97/23/ECEN10216-5 TC16)
ASTM A789PED 97/23/ECEN10216-5 TC1
Tolerances according to EN ISO 1127Outside diameter
Classes Tolerances
D1 ±1,5%, but min. ±0.75 mm
D2 ±1,0%, but min. ±0.5 mm
D3 ±0,75%, but min. ±0.3 mm
D4 ±0,50%, but min. ±0.1 mm
Wall thickness
Classes Tolerances
T0 ±20%, but min. ±1 mm) 1)
T1 ±15%, but min. ±0.6 mm
T2 ±12.5%, but min. ±0.4 mm
T3 ±10%, but min. ±0.2 mm
T4 ±7.5%, but min. ±0.15mm
T5 ±5%, but min. ±0.1 mm
1) SS 219711, condition 22, e.g. 3R12 = SS 2352-222) 3R65 = TP 316L (S31603)3) Incl. IC = Intergranular Corrosion test acc. to ASTM A 262 Pr.ENACE MR 0175/ISO 151564) Tolerances and leak test acc. to ASTM A312/A9995) Heat analysis and tensile strength. IC test in delivery condition6) The leakage test is deferred to the finished component. IC-test in delivery condition
8) Hot worked tolerances ASTM A99910) Incl. IC test acc. to DIN 50914 (EN ISO 3651-2 Method A)11) Incl. corrosion test acc. to ASTM G-48 Method A12) IC-test in delivery condition13) Heat analysis and mechanical properties acc. to data sheet. Corrosion testacc. to ASTM G 48, Method A. Impact test (t ≥ 6mm).Micrographic test (400X) NACE MRO175 / ISO 15156-1:2001