Buyers usually know the grade before they know the mill: the line list names the specification and grade — API 5L X52 PSL2, for example — and the pipe is ordered to match. This page is the map of those choices. A53 covers welded and seamless pipe for mechanical and pressure applications at ordinary temperatures — water, air, steam at moderate duty, structural. ASTM A106 is the seamless high-temperature specification behind most process piping. API 5L grades (X42, X52 and X60 in the ERW listings; X52 and X60 PSL2 in the seamless catalogue examples) are line pipe, strength-graded by minimum yield, with PSL2 the more heavily tested product specification level.
Alongside the ASTM / API system, the DIN carbon grades St37, St44 and St52 appear in our ERW listings for European-specified projects — the same steel logic in a different naming system.
| Item | Range / Options |
|---|---|
| Specifications | ASTM A53, ASTM A106, API 5L; DIN St37 / St44 / St52 in the ERW range |
| Types | Seamless and ERW (see type pages) |
| Size range | NPS 1/2 - 48 across the programme |
| Wall thickness | Per ASME B36.10; the ERW listing runs Schedule 20 through XXS — range by type |
| Finish | Black (self colour / painted); hot-dip galvanised; 3LPE coated line pipe listed |
| Ends | Bevelled on the catalogue examples; other end finishes confirmed per product at enquiry |
Pairing Pipe With Fittings
Carbon pipe grades have carbon fitting partners, and the pairings are conventional for a reason: A106 pipe welds to A234 WPB butt weld fittings and A105 flanges; API 5L lines use the same WPB / A105 family in matching schedules, with higher-strength fitting grades where the line class demands. The carbon steel elbow page covers the fitting side; pipe and fittings can be put on one enquiry together, but the grade and chemistry of each item are assessed and confirmed for the specific product before order.
Schedules, in One Paragraph
The schedule number selects the wall for a given NPS — the same NPS in Schedule 40 and Schedule 160 shares an outside diameter and nothing else. Fittings, flanges and pipe must all be ordered on the same schedule per joint. Our pipe schedule chart guide gives the wall table for common sizes and the worked examples buyers ask for.
Finish and Protection
Black pipe is supplied with the mill finish or protective paint for transit; galvanised pipe suits water and outdoor service; line pipe can be supplied 3LPE coated for buried service. State the finish with the grade — it is part of the pipe's specification, not an afterthought.
Frequently Asked Questions
A53 or A106 for a steam line?
ASTM A106 is the high-temperature specification and the standard choice for steam and hot process lines. A53 serves general and utility duty. If the line runs hot under pressure, order A106.
What does the X number in API 5L X52 mean?
It is the minimum yield strength in thousands of psi: X52 means 52,000 psi minimum yield. Higher X grades allow thinner walls at the same pressure, which is why transmission lines climb the X scale.
Can carbon steel pipe be supplied galvanised?
Yes, hot-dip galvanised executions are listed, mainly in the ERW range for water, fire and structural service. Galvanised pipe is normally joined with threaded fittings rather than welded.
How do I state a carbon steel pipe order?
Give the specification and grade (for example API 5L X52 PSL2), the NPS and schedule or exact wall, the length basis, the end finish and the coating. With those five items the pipe — and its fittings — can be quoted without a clarification round.
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Send Your Specification
Tell us the size, schedule or pressure class, material grade and quantity for the carbon steel pipe you need. MOQ and lead time are confirmed in the quotation for your exact specification.