Sep 13, 2026Standards & Testing
Steel Pipe Buying FAQ: Standards, Grades, Sizes and Supply
Buyer FAQ on SPAI STEEL pipe supply: standards, grades, sizes, ordering data, quality documents, payment and delivery terms.
Quick answer: SPAI STEEL supplies carbon steel, alloy steel, stainless steel, duplex and nickel-based steel pipe, pipe fittings, flanges and valves to international standards. Buyers get a usable quotation fastest when they state pipe type, material standard and grade, outside diameter, wall thickness, length and quantity.
What products and materials does SPAI STEEL supply?
Hunan Spai Pipe Industry Co., Ltd, trading as SPAI STEEL, is a subsidiary of SP Group founded in 1996 and exporting to more than 100 countries. The company runs two production bases: carbon steel in Jinghai, Tianjin, and stainless and alloy steel in Longwan, Wenzhou. The range covers carbon steel, stainless steel, duplex and super duplex steel, nickel-based alloy, copper-nickel alloy and titanium, together with alloy grades such as P11, P9 and P22 and the low-temperature grade A333 Gr.6. Products include seamless and welded pipe, buttweld fittings such as 90-degree elbows, tees, reducers and stub ends, plus flanges and valves supplied as a system solution.
Which standards and grades are used?
SPAI STEEL works to GB, API, ASTM, ASME/ANSI, BS, DIN, JIS and GOST standards. Stainless steel pipe is commonly ordered to ASTM A312 in grades such as TP304, TP304L, TP316 and TP316L, while seamless alloy pipe is commonly ordered to ASTM A335 in grades such as P11 and P22. Low-temperature service commonly uses ASTM A333 Gr.6. Because grades, tolerances and test requirements differ between standards, buyers should always state the exact standard and grade rather than a generic material name.
What sizes and schedules are available?
Seamless stainless steel pipe is commonly supplied from 1/8 inch up to 48 inch outside diameter, with wall thicknesses and pressure ratings from SCH10S through XXS. Exact availability depends on material, standard and mill schedule, so outside diameter and wall thickness should be confirmed at the enquiry stage instead of being assumed from a nominal size.
How should an enquiry be written?
For pipe and tube, give the pipe type (seamless or welded), material standard and grade, outside diameter, wall thickness, length and quantity. A typical line reads: seamless pipe, ASTM A312 TP316/316L, 10 inch, SCH40S, 6 m fixed length, 100 pieces. For buttweld fittings, add the fitting type, radius, size, schedule, material standard and test level, for example a 90-degree long-radius elbow, 12 inch, SCH10S, ASTM A403 WP316L, ASME B16.9, with 100 percent X-ray test. Forged socket-weld and threaded fittings should state size, class, schedule or thread type, material and dimensional standard. Flanges should state type, facing, size, class, thickness, material grade and standard. Valves should state type, port, size, class, connection, body and trim material and the applicable fire and test standards.
A complete specification is the fastest route to an accurate quotation: pipe type, standard and grade, outside diameter, wall thickness, length and quantity.
How is quality verified and documented?
Materials are sourced from approved manufacturers and supplied to the stated standard. SPAI STEEL performs testing before shipment, and third-party inspection by SGS, BV, TUV or TUBOSCOPE can be arranged. A mill certificate to EN 10204 is provided with shipment. Additional documents such as heat treatment reports, non-destructive testing reports, mechanical property reports and pressure test reports are available on request. Manufacturer audits can be accommodated for end users or third-party inspectors.
What are the payment and delivery terms?
Payment is commonly by T/T, with irrevocable L/C available for larger amounts subject to a downpayment, particularly for special grades and non-standard dimensions. Common delivery terms include FOB, CFR, CIF and EXW. Normal delivery is commonly about five weeks and depends on order quantity and raw material stock, so the schedule should be confirmed for each enquiry.
FAQ
Are you a manufacturer or a trading company?
SPAI STEEL is a manufacturer and exporter within SP Group, with carbon steel production in Tianjin and stainless and alloy steel production in Wenzhou. Flanges and valves are sourced from qualified third-party manufacturers to complete a full system package.
Can one order combine different materials and product types?
Yes. Because a project list often includes pipe, fittings, flanges and valves in several materials, items can be combined and collected from different qualified suppliers under one order, subject to confirmation of the actual items and conditions.
What documents are provided with a shipment?
A mill certificate to EN 10204 is standard, with heat treatment, NDT, mechanical performance, intergranular corrosion and pressure test reports available on request. Third-party inspection certificates can be issued when inspection is ordered.
What delivery terms and inspection options are available?
Common terms are FOB, CFR, CIF and EXW. Inspection options include in-house testing before shipment and third-party inspection by SGS, BV, TUV or TUBOSCOPE.
To discuss a current requirement, send the full specification to the SPAI STEEL sales team for a quotation and a delivery assessment.
