Stainless steel 904L tube is what plants switch to when 316L starts failing in acid. There’s roughly 25% nickel, 4 to 5% molybdenum, and a bit of copper, 1 to 2%. Most grades don’t have copper at all, and it’s the copper that lets 904L stand up to sulphuric and phosphoric acid. The nickel and molybdenum take care of the other problem, warm salty water, which pits 316L faster than most people expect.
We supply 904L as seamless tube for heat exchangers and pressure lines, and as welded tube for larger sizes where cost matters more. Tell us the acid, its strength and the temperature, and we’ll say plainly whether 904L is worth paying for. Metinox Overseas ships from Mumbai, with a mill test certificate on every lot.
This page covers 904L tubes only. For pipe in the same grade, see our stainless steel 904L pipe page, and for the full tube range, see our stainless steel tubes page.
Ready with your size and quantity? Request a quote for stainless steel 904L tubes.
Table of Contents
Stainless Steel 321 Tube Specification & Standards
| Specification | Detail |
|---|---|
|
Standards |
ASTM B677 and ASME SB677 for seamless tube, ASTM A213 and ASME SA213 TP 904L for seamless tube, ASTM A249 and ASTM A269 for welded tube |
|
Grade and UNS |
TP 904L, UNS N08904 |
|
Types |
Seamless, welded, EFW |
|
Seamless tube size |
OD 3.2 mm to 127 mm |
|
Welded and ERW tube size |
OD 6.35 mm and up |
|
EFW tube size |
Larger bores, from about 150 mm OD |
|
Wall thickness |
0.4 mm to 12.7 mm |
|
Length |
Single random, double random or cut length |
|
Condition and finish |
Solution annealed and pickled, or bright annealed |
|
Tolerances |
Per ASTM A1016 and the product standard |
|
Certificates |
EN 10204 3.1, with 3.2 on request |
Where 904L Stainless Steel Tubing Is Used
904L stainless steel tubing earns its price where acid or chlorides shorten the life of lesser grades.
- Chemical processing. Sulphuric and phosphoric acid lines are the grade's original job.
- Fertiliser plants. Phosphoric acid and warm process liquors attack 316L quickly.
- Flue gas desulphurisation. Wet, acidic gas with chlorides suits a high molybdenum steel.
- Pulp and paper. Bleaching liquors and hot chloride streams call for better pitting resistance.
- Heat exchangers and condensers. Aggressive cooling water and seawater cooling duty.
For instrument lines, see our instrumentation tubes, and for polished finish, see our bright annealed tubes.
Frequently Asked Questions
904L carries about 23 to 28 percent nickel, 4 to 5 percent molybdenum and 1 to 2 percent copper. 316L has 2 to 3 percent molybdenum and no copper. That is why 904L copes with sulphuric and phosphoric acid and hot chlorides where 316L pits or corrodes.
UNS N08904 is the number for grade 904L in the Unified Numbering System. The European number is 1.4539. It is a high alloy austenitic steel with very low carbon.
ASTM B677 is the specification for seamless and welded UNS N08904 tube, and TP 904L is the grade name used for the tube. Buyers often quote it next to ASTM A213, which covers the same grade as a stainless steel tube specification.
Both cover seamless 904L tube. B677 is written as a nickel alloy product specification, while A213 is the stainless steel tube specification used for boilers and heat exchangers. The minimum yield strength is about 220 MPa under B677 and about 215 MPa under A213, so name the one your drawing calls for.
It is made both ways. Seamless 904L tubes suit pressure lines and heat exchangers. Welded, ERW and EFW tubes suit process lines and larger bores at a lower cost.
ERW stands for electric resistance welded, where rolled strip is joined with heat and pressure and no filler is added. EFW stands for electric fusion welded, where rolled plate is welded to reach larger diameters. ERW covers small to medium sizes and EFW covers larger bores.
Seamless tube runs from about 3.2 mm to 127 mm OD and welded or ERW tube starts at about 6.35 mm OD. EFW tube covers larger bores from about 150 mm OD. Wall runs from about 0.4 mm to 12.7 mm. Send us your OD, wall and length and we will confirm.
Tolerances follow ASTM A1016 and the product standard. OD tolerance depends on the tube size, and wall tolerance is set as a percentage of the nominal wall. Table 5 on this page lists the limits by size range.
The carbon limit is 0.020 percent maximum. Some price lists show 0.20 by mistake, which is ten times too high. The low carbon helps the tube keep its corrosion resistance after heating.
The minimum tensile strength is 490 MPa and the minimum elongation is 35 percent. The minimum yield is about 215 MPa under A213 and about 220 MPa under B677. These are minimums from the standard, not typical test values.
Annealed 904L is non magnetic. Cold work such as bending can make it slightly magnetic, which is normal and does not mean the grade is wrong.
904L was developed for sulphuric acid and it also handles phosphoric acid well. It resists chloride pitting better than 316L. Strong hydrochloric acid and very hot concentrated acids need a different alloy, so send us your duty and we will advise.
Request a Quote for Stainless Steel 904L Tube
Tell us the form, OD, wall, length and quantity, and we will respond with the right 904L tube for your line. You can also browse all of our stainless steel tubes.
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