Standards glossary

The governing specification for stainless process pipe in grades such as TP304L and TP316L. It covers seamless, welded and heavily cold worked pipe, and sets the chemistry, mechanical properties, heat treatment and hydrostatic or eddy current testing. When you order stainless pipe for process duty, this is almost always the specification you are ordering to.

Covers larger diameter fusion welded stainless pipe intended for corrosive or high-temperature service. It defines five classes depending on whether the weld is radiographed and whether filler metal is added, so the class matters as much as the grade when you specify it.

The standard carbon steel pipe specification for refinery and power service, most commonly supplied as Grade B. Unlike A53 it is seamless only, and it carries tighter chemistry and mechanical requirements suited to elevated temperature.

A general-purpose carbon steel pipe standard covering black and galvanised, welded and seamless pipe. Type F, E and S denote furnace butt welded, electric resistance welded and seamless. Suited to utility, fire and low-pressure service rather than critical process duty.

The low-temperature carbon and alloy pipe standard, most often Grade 6. Its defining requirement is Charpy impact testing at low temperature, which is what qualifies the pipe for cryogenic and cold climate service.

Covers duplex and super duplex pipe in grades such as S31803, S32205, S32750 and S32760. It sets composition, solution annealing and mechanical requirements. Ferrite content control is central, because the balance of ferrite and austenite is what gives duplex its strength and chloride resistance.

The dimensional standard for flanges up to NPS 24 in Classes 150 through 2500. It fixes flange outside diameter, thickness, bolt circle, bolt count and facing, and gives the pressure-temperature ratings by material group. Two flanges of the same class and size to this standard will always bolt together.

The dimensional standard for butt weld elbows, tees, reducers, caps and stub ends. It sets centre-to-end dimensions, wall thickness tolerances and marking, so a B16.9 fitting will always match the pipe it is welded to.

Covers small-bore forged fittings — elbows, tees, couplings, unions and caps — in socket weld and threaded form. Rated by class (2000, 3000, 6000, 9000) rather than by schedule, and normally used below NPS 2.

Defines the standard pipe sizes and wall thicknesses for carbon and alloy steel — the source of Sch. 40, 80, 160 and XXS. Outside diameter is fixed for a given NPS, so increasing the schedule reduces the bore rather than enlarging the pipe.

The stainless equivalent of B36.10M, defining the S schedules — 5S, 10S, 40S and 80S. The thinner S walls exist because stainless does not need a corrosion allowance in most service, so the pipe can be lighter for the same duty.

The specification for pipeline steel used in oil and gas transmission, in grades from B up to X80. It is issued at two product specification levels: PSL1 is the basic standard, PSL2 adds mandatory chemistry, impact testing and traceability requirements.

Sets out which materials may be used in sour service and under what conditions, with limits on hardness, heat treatment and cold work. It applies to the whole assembly — pipe, fittings, flanges and bolting — and compliance must be demonstrated on the certificate, not assumed from the grade.

The European directive governing the design, manufacture and conformity assessment of pressure equipment. Materials supplied into PED scope need an appropriate material approval and 3.1 or 3.2 certification. Steelman Piping Solutions is PED certified.

A certificate issued by the manufacturer, validated by an inspection representative independent of the production department, confirming that the product meets the order requirements and stating the actual test results. This is the standard MTC supplied with our material.

The same as a 3.1 certificate but countersigned by an independent third-party inspector or the customer’s own representative. Required where a client or authority stipulates external witness of the testing.

The Indian statutory framework governing boilers and boiler-connected piping. IBR-certified pipe and fittings are supplied with Form III-C certification approved by the relevant boiler inspectorate, and are frequently a contractual requirement on Indian power and process projects.

A calculated index of a stainless steel’s resistance to chloride pitting: PREN = %Cr + 3.3 × %Mo + 16 × %N. 316L sits around 25, duplex 2205 around 35, and super duplex above 40. It is a comparison tool, not a guarantee of performance in a given service.