Background: Why Several Standards Exist
Stainless steel piping products are divided into pipe and tube, and within each category by diameter, wall thickness, and service temperature. Rather than one universal standard, the industry uses several ASTM specifications, each covering a defined product family. ASTM A312 covers seamless and welded austenitic stainless steel pipe for general and corrosive service. ASTM A213 covers seamless ferritic and austenitic boiler, superheater, and heat exchanger tubes. ASTM A269 covers seamless and welded austenitic tubing for general service, especially small diameters. ASTM B673, B674, and B677 cover welded, welded-and-cold-drawn, and seamless pipe of specific nickel-containing stainless grades with enhanced corrosion resistance. Understanding which standard applies is the first step in any compliant material specification.
ASTM A312: General Stainless Pipe
A312 is the default specification for austenitic stainless steel pipe in diameters from 1/8 inch to 30 inches and beyond, in schedules such as 5S through 160 and XXS. It covers grades including 304, 304L, 316, 316L, 321, 347, and 310S. The standard requires chemistry per grade, tensile and hardness testing, flattening and bending tests for welded pipe, and hydrostatic or nondestructive examination. Pipe to A312 is used in chemical plants, food processing, water treatment, and general corrosive service where the design pressure and temperature are moderate.
ASTM A213: Boiler and Heat Exchanger Tube
A213 covers small-diameter seamless tube used in boilers, superheaters, and heat exchangers, with outside diameters up to about 5 inches. The standard includes austenitic grades such as TP304H, TP316H, TP321H, and TP347H and ferritic grades such as T11 and T22. Because the product is designed for elevated-temperature service, A213 requires additional tests including flattening, flaring, and often elevated-temperature tensile data, and the heat-treatment condition is specified to guarantee creep and rupture performance.
ASTM A269: General Service Tubing
A269 covers seamless and welded austenitic tubing for general corrosion-resisting and low- or high-temperature service, with a size range overlapping A213 but not limited to boiler duty. It is the common specification for small tubing in instrumentation, hydraulic lines, and heat exchangers where tight tolerances and clean bores are needed. The standard includes the same workhorse grades as A312 and allows either annealed or lightly cold-worked conditions depending on the grade.
ASTM B673, B674, and B677: High-Alloy Corrosion Pipe
The B-series standards cover pipe of high-alloy stainless and nickel-containing grades for aggressive chemical service. B673 covers welded pipe, B674 covers welded-and-cold-drawn pipe, and B677 covers seamless pipe. Typical grades include the low-carbon 20-type alloys and UNS N08904, N08925, and N08926, which resist chlorides, sulfuric acid, and pitting and crevice corrosion far better than the 300-series grades. These products are specified for chemical processing, flue gas desulfurization, and offshore seawater systems.
Selection Guidance
| Application | Recommended Standard |
|---|---|
| Process piping in plants | ASTM A312 |
| Boiler and superheater tubes | ASTM A213 |
| Instrument and heat exchanger tubing | ASTM A269 |
| Severe chloride and acid service | ASTM B673, B674, B677 |
Frequently Asked Questions
The applicable standard depends on the product and service: API 5L for line pipe, ASTM A53 and A106 for carbon steel pipe, ASTM A312 and A213 for stainless steel, and ASME B16 series for dimensions and fittings; the order should name the standard and its edition.
Sizes range from small bore to large diameter per the product standard, with wall thickness expressed in schedule numbers from SCH10 to XXS or in millimetres; the order states the outer diameter, wall thickness and length.
Carbon steel grades such as API 5L B through X70 and ASTM A106 B, alloy steels, and stainless grades such as 304/304L, 316/316L and duplex are available, each delivered with certified chemistry and mechanical properties.
Each lot is tested for chemical composition, mechanical properties, dimensions and pressure integrity, with hydrostatic testing and non-destructive examination per the standard, and the certificate documents the results.
Black painted, varnished, oiled, galvanized or coated surfaces are available, with plain, beveled or threaded ends; plastic caps and steel end protectors protect the pipe during transport.
Store on skids off the ground with the ends protected, keep it dry and away from dissimilar metals, and lift bundles with slings at the specified lift points to avoid damage.
