Standards · ASME and ASTM · ASTM A234/A234M
ASTM A234/A234M: Piping fittings of wrought carbon steel and alloy steel for moderate and high temperature service
The material standard of the carbon and alloy steel buttwelding fittings to B16.9 (and forged fittings to B16.11): chemistry, strength, heat treatment and testing of elbows, tees, reducers and caps made from pipe, plate or forgings.
- Issued by
- ASTM
- Edition (publisher, as of 2 October 2026)
- 2026
- Material specification
- Piping fittings of wrought carbon steel and alloy steel for moderate and high temperature service
- European counterpart
- EN 10253-2 (P235GH 1.0345, P265GH 1.0425, 16Mo3, 13CrMo4-5, 10CrMo9-10, X10CrMoVNb9-1)
- Belongs with
- ASME B16.9 · ASTM A106/A106M · ASTM A105/A105M · ASTM A420/A420M
- At Zickwolff
- we carry – from stock or to order, lead time on request
Scope: sizes, classes, grades
Grades WPA, WPB and WPC (carbon steel) and WP1, WP5, WP9, WP11, WP12, WP22, WP91 (alloy, with classes). WPB is the standard: tensile 415 to 585 MPa, yield min. 240 MPa, carbon max. 0.30 %, use range about −29 °C to 425 °C, no impact requirement. Welded fittings carry the suffix W, seamless S.
Product form
Wrought fittings, seamless or welded, from killed steel pipe, plate, bar or forgings.
Grades and their European counterparts
| Grade | Type | Tensile / yield min. (MPa) | European counterpart | Limits of the comparison | At Zickwolff |
|---|---|---|---|---|---|
| WPA | carbon steel | not stated in our sources | P235GH 1.0345 · EN 10253-2 | comparable by strength, not identical in analysis | on request |
| WPB | carbon steel | 415 / 240 | P265GH 1.0425 · EN 10253-2 | comparable by strength, not identical in analysis | deliverable |
| WPC | carbon steel | 485 / 275 | not stated in our sources | no common EN grade – compare by analysis and certificate | on request |
| WP1 | alloy steel | not stated in our sources | 16Mo3 1.5415 · EN 10253-2 | comparable by strength, not identical in analysis | on request |
| WP11 Cl. 1 | alloy steel | not stated in our sources | 13CrMo4-5 1.7335 · EN 10253-2 | comparable by strength, not identical in analysis | deliverable |
| WP12 Cl. 2 | alloy steel | not stated in our sources | 13CrMo4-5 1.7335 · EN 10253-2 | comparable by strength, not identical in analysis | on request |
| WP22 Cl. 1 | alloy steel | not stated in our sources | 10CrMo9-10 1.7380 · EN 10253-2 | comparable by strength, not identical in analysis | on request |
| WP5 | alloy steel | not stated in our sources | X11CrMo5 1.7362 · EN 10253-2 | comparable by strength, not identical in analysis | on request |
| WP9 | alloy steel | not stated in our sources | X11CrMo9-1 1.7386 · EN 10253-2 | comparable by strength, not identical in analysis | on request |
| WP91 | alloy steel | 585 / 415 | X10CrMoVNb9-1 1.4903 · EN 10253-2 | comparable by strength, not identical in analysis | on request |
WPB is compared with P265GH (WPA with P235GH), WP1 with 16Mo3, WP11/WP12 with 13CrMo4-5, WP22 with 10CrMo9-10 and WP91 with X10CrMoVNb9-1 – all fittings to EN 10253-2.
Use in Europe: the Pressure Equipment Directive
Under the Pressure Equipment Directive an ASTM material has no presumption of conformity: it needs a European material approval or a particular material appraisal (PMA) by the equipment manufacturer, in categories III and IV assessed by the notified body. Comparisons with EN grades are orientation, never a one-to-one equivalence – chemistry bands, test scope and certificate differ. An EN fitting keeps the pipe material name (P265GH), an ASME fitting gets its own grade (WPB) – the same steel, two names. WPB tolerates higher phosphorus and sulphur than P265GH.
Marking on the part
Via B16.9: manufacturer, WPB (or WP11 etc.), schedule or wall, NPS, heat number – e.g. 12 STD WPB with heat code.
The standard family: dimensions, material, pipe
ASME B16.9 · ASTM A106/A106M · ASTM A105/A105M · ASTM A420/A420M
At Zickwolff
Buttwelding fittings A234 WPB to B16.9 are part of our range in the common schedules, alloy grades WP11 and WP22 we procure – with certificate 3.1, matching A106 pipe and A105 flanges from one source.
Dimensions Dimension tables for this standard are available on request – we work from manufacturer catalogues, not from copied standard tables.
Further reading
The profiles: ASME B16.5 · ASME B16.9 · ASME B16.25 · ASME B36.10M · ASME B36.19M · ASTM A105/A105M · ASTM A106/A106M · ASTM A182/A182M · ASTM A333/A333M · ASTM A350/A350M · ASTM A403/A403M · ASTM A420/A420M · ASME and ASTM standards.
From our pages: Flange dimensions ASME B16.5 Class 150/300 · DIN/EN or ASME for flanges · Standards guide · Materials · Pipe dimension tables · Rule of thumb: Class 150 is not 150 psi · Rule of thumb: schedule is not a wall thickness · Rule of thumb: DN is not a diameter.
Frequently asked questions about ASTM A234/A234M
Can I use this ASTM material in a pressure line under the PED?
Yes, but without presumption of conformity: the equipment manufacturer needs a European material approval or a particular material appraisal (PMA), in categories III and IV assessed by the notified body. For equipment under Article 4(3) (sound engineering practice) this does not apply. We supply the material with certificate 3.1 – the appraisal is the manufacturer's.
Must a plant with ASME parts be inspected more often?
No – the inspection interval comes from the operating law of the country, not from the code of the part. In Germany the Betriebssicherheitsverordnung (Annex 2 Section 4) sets maximum intervals, the operator fixes the interval in the risk assessment and the inspector may shorten it (TRBS 1201 Part 2) where design or manufacture give reason to. Operators often inspect more frequently anyway. This is general information, not legal advice – the legal text is binding.
WPB or P265GH on the fitting?
The same kind of steel under two names: an EN fitting keeps the pipe material name, an ASME fitting gets the fitting grade WPB. Which one you need depends on the design code of the line.
What do W and S after the grade mean?
W = welded, S = seamless fitting – the certificate tells which, and for welded fittings which test of the fitting weld was made.
Parts to ASME and ASTM – from one source
Tell us standard, size (NPS and schedule or Class), material grade, certificate and quantity – we check what is in stock, what we procure and which European part would do the same job.
Send an inquiryYour inquiry to Zickwolff
Send us what you have – designation, standard, quantity, date. We will clarify the rest with you.
One item or a question
Send inquiry
Not in stock? We procure it – single items too.
Designation, standard and quantity are enough.
Several items
Send bill of materials
200 items? One parts list is enough – we deliver complete.
Attach it as a file.
Helpful if already known: project and country, date needed, certificates, packaging and language of the packing lists. If anything is missing, we will ask.
It is urgent
Request express
When do you need it? Express delivery, to the site if required.
Tell us by when you need the material – we will tell you what is possible.
Basis: the publicly accessible scopes and abstracts of ASME and ASTM (editions as of 2 October 2026), manufacturer catalogues, a trade reference catalogue DIN/EN/ASME and specialist sources for marking and impact test values – the legal statements follow Directive 2014/68/EU and the German Betriebssicherheitsverordnung. No standard text was reproduced – the current original edition is binding. Comparisons with EN grades are orientation, not equivalence. Information without guarantee, no legal advice, no prices.