How to Read ASTM Material Codes

Most of the confusion on enquiry lists comes from material codes. Once the logic is clear, it takes one glance to know what an item is.

Structure of the code

An ASTM code has two parts: the standard number and, where applicable, the grade.

• A105: A single grade standard; no further designation needed
• A182 F316L: Standard A182, grade F316L
• A350 LF2 Class 1: Standard A350, grade LF2, class 1
• A234 WPB: Standard A234, grade WPB
• A193 B7 / A194 2H: Stud and nut standards with their grades

The letter A before the number denotes ferrous materials. In metric designation the same standard may appear as "A105M".

Codes in common use

The logic of the letters

Forgings carry the prefix F, fittings WP (wrought product) and pipes TP (tube product). A trailing L indicates low carbon content, which preserves corrosion resistance after welding. On the fastener side, B grades are alloy steel and the B8 family is stainless.

On the order

Write standard and grade together; "stainless flange" or "A182 flange" is not enough. A correct line reads: *ASME B16.5, 4", 150#, RF, WN, ASTM A182 F316L, EN 10204 3.1.*

Use our material equivalence tool to compare grades by service class, and send your list through the enquiry form.

FAQ

Is A182 enough on its own?
No. A182 is a standard and must be written with a grade such as F316L.

What does the L mean?
Low carbon content, which preserves corrosion resistance in the weld zone.

What do WP and TP mean?
WP is used for wrought fittings and TP for tube products.