Frequently Asked Questions

No. NPS 2 pipe has an outside diameter of 60.3 mm, not 2 inches. From NPS 14 upward the outside diameter equals the nominal size in inches, but below that it does not.

No. For a given NPS the outside diameter is fixed, so changing schedule changes the bore and the flow area while everything still bolts together.

Only up to NPS 10. From NPS 12 upward STD is a constant 9.53 mm, so at NPS 16 STD gives 9.53 mm against 12.70 mm for Sch 40. XS equals Sch 80 only up to NPS 8.

Not across the range. The S series under ASME B36.19M is a parallel designation for stainless and alloy pipe. Full detail in thepipe schedule guide.

No. A flange has a class because its geometry is standardised; pipe capacity is calculated from wall, grade and design temperature. See thepipe pressure rating chart.

No, and on sour service it makes things worse. Hardness rises with strength while the sour limit does not move, so a thicker wall at a lower grade qualifies more easily.

Not inherently. In hot chloride service the austenitic structure is what cracks, so a ferritic or duplex grade can outperform 316L. See thematerial selection guide.

Only as an approved deviation. Chemistry ranges, test temperatures and delivery conditions differ, so it is not a translation.

No. It can be met by S31803 or S32205, and the two differ in nitrogen floor, which matters on welded work. See theduplex vs super duplex guide.

Because several grades have them and the class changes the properties. A234 WP11 has three classes with different minimum tensile strengths, and the class is frequently left off the order.

Who validates it. A 3.1 is certified by the manufacturer's inspection department independent of production; a 3.2 is also validated by an independent inspector or the purchaser's representative. The tests can be identical.

No. A 3.2 requires witnessed testing, so it must be arranged before the tests happen.

A 2.2 reports non-specific inspection, so the tests were not necessarily on the material supplied. A 3.1 reports specific inspection on that material. That gap is larger than the one between 3.1 and 3.2.

Yes. Projects are qualified against a stated edition, so material certified to a different one creates a documentation gap at handover. See theMTC and EN 10204 guide.

At a hydrogen sulphide partial pressure of 0.3 kPa, equal to 0.05 psi. Below that, ISO 15156 does not apply.

Because ISO 15156-2 defines severity using partial pressure and in-situ pH together, so both numbers are needed before a material can be assessed.

Essentially only API 5L PSL2 Annex H line pipe and correctly specified API 5CT grades. Fittings, flanges, bar, bolting and gaskets all need it ordered. See theNACE guide.

No. HIC resistance comes from steelmaking cleanliness, so it determines where the material is made.

Only the impact test report with its test temperature. A106 Gr B and A333 Gr 6 cannot be separated by chemistry or by PMI.

No. B7 is not a low temperature grade. Cold service needs A320 L7, L43 or L7M studs with A194 Grade 4 or 7 nuts. Seefasteners and bolting.

Because the wall at the weld end has to match, and a mismatch gives a poor root. It is the commonest dimensional error on a piping order.

No. Same class, different bolting pattern and thickness. The series must be stated.

The pipe is withdrawn about 1.6 mm from the bottom of a socket before welding so the weld does not absorb differential expansion. See thefittings guide.

Yes. The finish is specified as a range, because too rough prevents sealing and too smooth leaves the gasket nothing to grip.

It is ordered to a schedule, and a mismatch leaves a permanent internal step that cannot be corrected after welding.

Specification and grade with class, dimensional standard and size, schedule or wall or class, quantity, delivery point and required date. Full checklist on therequest for quotation page.

Send the service conditions instead. A guessed grade produces a priced offer for the wrong material.

USD, OMR, AED, SAR, QAR, KWD and BHD, on EXW, FOB, CFR or CIF terms.

No. Lead time is confirmed at quotation, because on alloy items availability in the exact grade and size governs rather than tonnage.

No stock claim is made on this site because it has not been confirmed. Ask directly if availability affects your decision.

Oman, including Muscat, Sohar, Duqm, Salalah and Sur, and the wider GCC. Seelocations.