Building and civil works buy steel pipe for four separate jobs: carrying water, carrying fire protection, carrying the structure itself, and standing in the ground as a pile. The specification follows the job rather than the other way round, which is why two pipes of the same diameter on the same site can be different purchase items.
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What each job decides
Water and drainage pipe is selected for what it carries and where it sits. Buried mains are usually steel pipe with a cement-mortar lining to stop tuberculation and an external coating to survive the soil, while above-ground distribution and plumbing pipe is normally hot-dip galvanized to resist atmospheric corrosion. Fire protection is its own case: the system is hydraulically designed, and the pipe is bought to ASTM A53 or ASTM A795 in Schedule 10 or Schedule 40 depending on what the design requires.
Structural and piling work uses pipe as a load-bearing member. Pipe piles are welded or seamless steel pipe driven or bored into the ground, and the wall thickness is set by the driving stresses and by a corrosion allowance for the soil and water table rather than by the working load alone. Round structural sections are bought against their own specification, which is not the same as a pressure-pipe specification even when the diameter matches.
Coating and lining are chosen with the ground
For buried steel water pipe, the lining and the coating are both part of the specification. Cement-mortar lining gives a durable internal surface and a slight flow benefit; liquid-epoxy lining is used where the water chemistry or the flow requirement calls for it. Externally, a three-layer coating system is the usual answer for burial, and where the pipe is exposed, galvanizing to the required coating weight is common. The point to hold on to is that the coating is priced and inspected separately from the pipe, so it belongs in the enquiry from the start.
What is normally called out
| Service need | Product | Standard and grade |
|---|---|---|
| Buried water mains | Anti-Corrosion Coated Steel Pipe | Cement-mortar or epoxy lined; 3LPE coated; to the project specification |
| Exposed and distribution water pipe | Hot Dip Galvanized Steel Pipe | ASTM A53 galvanized, zinc coating weight specified |
| Fire protection systems | ASTM A53 Steel Pipe | ASTM A53 or A795, black or galvanized, Schedule 10 or 40 |
| Piling and structural round sections | API 5L ERW Welded Steel Pipe | ASTM A252 for pipe piles; structural rounds to their own spec |
| Steam, condensate and high-pressure services | ASTM A106 Seamless Carbon Steel Pipe | ASTM A106 grades A, B, C |
| Direction changes and offsets | Butt Weld Elbow | ASME B16.9, ASTM A234 WPB |
| Branch take-offs and headers | Butt Weld Tee | ASME B16.9, ASTM A234 WPB |
| Small-bore connections | Threaded Fittings | ASME B16.11, ASTM A105 / A182 |
| Mechanical and socket joints | Socket Weld Fittings | ASME B16.11, ASTM A105 |
| Flanged connections to plant | Pipe Flanges | ASME B16.5, ASTM A105, A182 F316 |
Specifying a construction order
Most construction enquiries are a bill of quantities rather than a single specification, so the useful things to supply are the standard, the grade, the nominal size, the schedule or wall thickness, the length, the coating or lining, and the quantity by item. Where the pipe is purchased against a project specification rather than a national standard, that document governs and should be sent with the enquiry, because it will usually impose its own coating system and documentation requirements.
- Say whether the pipe is buried or exposed. It changes the coating, and coating is a real part of the price.
- Name the schedule, not just the size. Schedule 10 and Schedule 40 pipe of the same nominal size are different weights and different prices.
- State the lining where water is carried. Cement-mortar and epoxy lining are not interchangeable on a specification.
- Give the zinc coating weight for galvanized pipe. The coating requirement is a separate line from the pipe itself.
- Confirm whether the pipe piles need a corrosion allowance, and how much. It changes the wall thickness and the tonnage.
- Send the project specification if there is one. It overrides the default standard and usually adds documentation.
Frequently asked questions
What is the difference between ASTM A53 and ASTM A795 pipe?
Both cover steel pipe for ordinary service. A795 is written specifically for fire protection systems, covering black and hot-dipped zinc-coated welded and seamless pipe, while A53 is the general-purpose specification. Where a fire protection design calls out A795, the pipe should be ordered to A795 rather than substituted with A53.
Which pipe is used for fire protection systems?
Steel pipe to ASTM A795 or ASTM A53, in Schedule 10 or Schedule 40 depending on the hydraulic design of the system. The size and schedule come from the design calculation and the hazard classification, not from a rule of thumb, so the schedule belongs on the enquiry.
Why is a corrosion allowance added to pipe piles?
Because a pile is designed to carry its load for the life of the structure while sitting in soil and groundwater that will corrode it. The section that is lost to corrosion over the design life cannot carry load, so the wall thickness is increased beyond the structural requirement to allow for that loss.
Do you supply cut lengths and fabricated spools?
Pipe is normally supplied in standard random or fixed lengths, and cutting, bevelling, coating and fabrication to a drawing are separate operations that should be agreed before the order is placed, because they change both the price and the delivery.
Where to go next
- Steel pipe weight calculator – work out the weight of any size and wall thickness
- Pipe schedule chart – wall thickness for every schedule, carbon and stainless
- Request a quotation – send the specification, quantity and destination port
- ASTM A53 Grade B pipe – the general-purpose construction specification in detail
- ASTM A106 Grade B pipe – the seamless equivalent for higher-pressure services
- ASTM A252 steel piling pipe – grades 1, 2 and 3 for driven piles and foundations
- Steel pipe and line pipe – seamless, ERW, LSAW and SSAW, coated and uncoated
Looking for a price on a specific item? We need the standard and grade, the size and wall thickness, the quantity, and the destination port. With those four we can confirm availability and give you a price.
Request a quotation