Material inspection and review MTC of piping fitting ASTM A234


ASTM A234: specification for piping fitting of wrought carbon steel and alloy steel for moderate and high-temperature service.

This specification cover wrought carbon steel and steel fitting of seamless and welded construction.

This specification does not cover cast welding fittings or fittings machined from casting.

Odering information and general requirement

See Pipe fitting ASTM A234 and order information requirement or ASTM A960.


Killed steel, forging, bars, plates, seamless or fusion-welded tubular product with filler added.

“fusion-welded tubular with filler added: SAW, GTAW (filler add), GMAW”.

MTC shall be cleared the marking specification such number, grades and date.

If product comply other standard, the MTC shall be stated the test result values.

“ex. NACE MR 0175, MTC shall state hardness value, forming and heat treatment, read more in NACE MR0175 part 1, 2, 3.


Forging or shaping operation by cold and hot forming.

NDE may be performed either prior to or after forming on welded product.

NDE reports shall state in the MTC and available review by purchase.

Heat treatment

Heat treatment shall be performed after forming, see para. 7 on ASTM A960

ASTM A234 WPB most finished by normalizing, Annualizing.

Other grades see section 7.0.

Chemical composition

See table 1.

It is identified as trace number, heat number, casting number, or heat code.

  • L- ladle: test on casting, another name heat, casing.

  • P- product: test on production after forming, see ASTM A960 for acceptance criteria.

Limitation of carbon equivalent (CE) % = C n+ Mn/6 + (Cr+Mo+V)/5 +(Ni+Cu)/15 are in the project specification and application.

And other content limitation in specification, don’t forget see any foot notes in each table.

If piping fitting formed from pipe, the MTC shall be stated “Material made from seamless pipe/welded pipe” and traceable heat number of pipe.

NDE reports such RT/UT MP/PT shall attach to MTC if fitting made from welded tubular.

Mechanical properties

See table 2 and ASTM A960.

If sample test on production, the MTC shall be clearly stated the sample dimension such standard roundness, rectangle, size, subsize… or it detailed in MTC of pipe, please check with manufacturer.

If sample dimensions were not state in the MTC, elongation value shall be excess 30%.


Fitting of all grades is allowed maximum 197 HB, except WP5, WP9, WPR, WP91, WP911.

Hydrostatic test

See ASTM A960 if PO requirement.


Dimension and tolerance given in ASME B16.9 for butt-weld fitting, ASTM B16.11 for threading/socket weld.

Surface quality

See ASTM A960.

Repair by welding

Most project prohibited, please check in PO requirement.


See section 17.

Product marking

It is a task of welding inspection to evaluate acceptance or rejection.

See MSS-P-25 and ASME B16.9, B16.11.

Read more: How to verify product marking for pipe fitting ASMT A234 WPB


The supplementary requirements shall apply only when specified by the purchaser in the inquiry, contract, and order such as CE%, hardness, heat treatment, NDE after forming, etc.


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