347/347H

UNS S34700

Availability

Seamless Pipe 1/2″ – 8″
Weld Pipe 8″ – 12″

Butt-Weld Fittings 1/2″ – 8″
Bar 1″ – 12″

Specifications

ASTM A312, A403, A182, A479, A276
ASME SA312, SA403, SA182, SA479, SA276

Chemical Composition

C	Co	Cr	Mn	Ni	P	S	Si	Ta
Max	-	-	Max	-	Max	Max	Max	-
0.08	Trace*	17.0 – 20.0	2.0	9.0 – 13.0	0.04	0.30	0.75	Trace*

The columbium plus tantalum content shall not be less than 10 times the carbon content and not more than 1.0% Note: 347H requires the columbium plus tantalum content to be not < 8 times the carbon content and not > 1.0%

These types of stainless are austenitic chromium steels containing columbium. They are recommended for parts fabricated by welding which cannot be subsequently annealed. These types also are used for parts which are intermittently heated and cooled to temperatures between 800 ̊ and 1600 ̊ F. The addition of columbium produces a stabilized type of stainless that eliminates carbide precipitation, and consequently, intergranular corrosion.

Superior general corrosion resistance over Type 321 due to stabilization with columbium.
Reduced tendencies to form continuous networks of chromium carbides at the grain boundaries.
Better high temperature properties than 304 or 304L. Generally used for parts which are intermittently heated up to 1500 ̊ F. For continuous service the maximum temperature is 1650 ̊ F.
Type 347H has high carbon (.04-.10) for better high temperature creep properties.
Improved intergranular corrosion resistance.

High temperature chemical process heat exchanger tubes
Refineries
High temperature steam service

Tensile Strength
(KSI)
75

Yield Strength
(KSI)
30

KSI can be converted to MPA (Megapascals) by multiplying by 6.895.

James Duva Inc. stocks 347 with high carbon to meet 347/347H specifications