In general, the quality of seamless stainless steel pipe fittings is better than that of seamless stainless steel pipe fittings, because the seamless stainless steel pipe fittings are made of the accurate cold-rolled sheet that has passed the inspection, so any defect is limited to the welding position. Seamless tube is made of stainless steel by punching, which leads to many tears in the tube wall formed by extrusion. The eddy current test shows that the defective rate of stainless steel tube with seam is usually lower than that of seamless stainless steel tube. Using ultrasonic testing, the background noise of seamless stainless steel pipe is so large that it is difficult to find its defects. However, the background noise of stainless steel pipe with seam is very low, so it is easy to find the defect.
Dual certified 304/304H is used as a material of construction up to 1500°F. Slight scaling begins at about 1200°F. This is the 0.04% minimum carbon version of type 304 stainless. It has general corrosion resistance similar to the low carbon 304/304L. However, it is subject to carbide precipitation in the heat affected zone (HAZ) of welds. Weldments may be sensitive to HAZ intergranular corrosion in oxidizing acid environments, and to polythionic acid stress corrosion cracking. The carbide precipitation is not harmful to high temperature mechanical properties.
304/304H is welded using the 22Cr 11Ni filler wire (ER308), or covered electrodes (E308). Post-weld heat treatment is not necessary for most high temperature service.
Chemistry
| | Cr | Ni | C | Mn | Si | P | S | Fe |
| MIN | 18.0 | 8.0 | 0.04 | – | – | – | – | – |
| MAX | 20.0 | 10.5 | 0.10 | 2.0 | 0.75 | 0.04 | 0.03 | Balance |
Specifications
AMS 5513
ASME SA 240
ASTM A 240, ASTM A 959
EN 1.4301
UNS S30400, UNS S30409
W. Nr./EN 1.4948
Werkstoff 1.4301
Inventory
304 / 304H Plate, 304 / 304H Welding Products
Common Trade Names
304H Stainless
Features
Elevated temperature service to 1500°F
Corrosion resistance similar to 304/304L
Applications
Pressure Vessels
Petrochemical Equipment
Physical Properties
Density: 0.285 lb/inch3
Temperature, °F 212 1600
Coefficient* of Thermal Expansion, in/in°F x 10-6 9.4 –
Thermal Conductivity Btu • ft/ft2 • hr • °F 9.4 10.9
* 70°F to indicated temperature.
Mechanical Properties
Representative Tensile Properties
| | Minimum | Typical |
| Ultimate Tensile Strength, ksi | 75 | 90 |
| 0.2% Yield Strength, ksi | 30 | 35 |
| Elongation, % | 40 | 60 |
Maximum Allowable Stresses, ASME Section VIII, Div 1 Temperature, °
| Temperature, °F | 200 | 400 | 600 | 800 | 1000 | 1200 | 1400 | 1500 |
| stress, ksi | 20.0 | 18.3 | 16.6 | 15.2 | 14.0 | 6.1 | 2.3 | 1.4 |
