SS 317 & 317L Pipes to ASTM A312

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SS 317 vs 317L Pipe: What Is the Difference?

The two grades share the same chromium, nickel and molybdenum ranges. Carbon is the only line that separates them, and it decides how the pipe behaves after welding.

Point of comparison	317 (UNS S31700)	317L (UNS S31703)
Carbon, max	0.08%	0.035%
Weld zone after welding	Can sensitise if held between about 425 and 815 °C	Resists sensitisation in normal welding
Post weld anneal for corrosion service	Often required	Usually not required
Strength at room temperature	515 MPa tensile, 205 MPa yield min	515 MPa tensile, 205 MPa yield min
Strength above about 425 °C	Slightly higher, helped by carbon	Slightly lower
Typical choice	Unwelded or annealed after fabrication	Welded process piping, the usual default
Dual certification	Possible when carbon meets 0.035% and strength meets 317	Same pipe, marked TP317/TP317L

Decision: specify 317L, or dual certified 317/317L, for welded systems. Keep straight 317 for jobs where the drawing or code calls for it by name.

317 Stainless Steel Pipe Specifications

Item	Details
Seamless and welded pipe	ASTM A312 / ASME SA312
Electric fusion welded large bore pipe	ASTM A358 / ASME SA358
Welded large diameter, annealed or as welded	ASTM A778 (317L)
Tolerances and general requirements	ASTM A999 / ASME SA999
Dimension standards	ASME B36.19M (5S to 80S), ASME B36.10M (heavier walls)
European equivalents	EN 10216-5 (seamless), EN 10217-7 (welded), 1.4449 / 1.4438
Outside diameter	1/8” to 24” NPS (10.3 to 610 mm); larger sizes in welded form
Wall	Sch 5S, 10S, 40S, 80S, 160 and XXS
Lengths	Single random (about 6 m), double random (about 12 m) or cut to length
Ends	Plain, bevelled to ASME B16.25, threaded
Finish	Pickled and passivated, annealed; bright annealed or polished on request
Heat treatment	Solution annealed at 1040 °C min, rapid cool
Certification	EN 10204 3.1; 3.2 through a third party

Note: write “ASTM A312 SS317L seamless” or “ASTM A312 SS317/SS317L welded”, followed by size, schedule, length and ends.

ASTM 317 Stainless Steel Pipe Chemistry

Element, %	SS 317 (S31700)	SS 317L (S31703)
Carbon	0.08 max	0.035 max
Manganese	2.00 max	2.00 max
Phosphorus	0.045 max	0.045 max
Sulphur	0.030 max	0.030 max
Silicon	1.00 max	1.00 max
Chromium	18.0 to 20.0	18.0 to 20.0
Nickel	11.0 to 15.0	11.0 to 15.0
Molybdenum	3.0 to 4.0	3.0 to 4.0
Iron	Balance	Balance

The pitting resistance equivalent number (PREN = %Cr + 3.3 x %Mo + 16 x %N) is about 28 to 33 for 317L, against about 24 to 26 for 316L. That gap explains most of the grade’s advantage in seawater cooled exchangers and bleach plant liquors.

Decision: check carbon first (it tells you whether the pipe can carry the L marking), then molybdenum (it must not fall below 3.0%).

SS 317 & 317L Pipe Mechanical Properties 

Property	SS  317	SS 317L
Tensile strength, min	515 MPa (75 ksi)	515 MPa (75 ksi)
Yield strength (0.2% offset), min	205 MPa (30 ksi)	205 MPa (30 ksi)
Elongation in 50 mm, min	35% longitudinal, 25% transverse	35% longitudinal, 25% transverse
Hardness, max (A240 plate reference)	95 HRB / 217 HB	95 HRB / 217 HB

What Are the Physical Properties of SS 317 & 317L Pipe?

Property	Value
Density	7.95 to 8.0 g/cm³ (0.287 lb/in³)
Modulus of elasticity	193 to 200 GPa
Mean thermal expansion, 20 to 100 °C	16.5 µm/m·°C
Mean thermal expansion, 20 to 500 °C	18.0 µm/m·°C
Thermal conductivity at 100 °C	14.4 to 16.2 W/m·K
Specific heat, 0 to 100 °C	500 J/kg·K
Electrical resistivity at 20 °C	0.79 µΩ·m
Melting range	1370 to 1400 °C
Magnetic response, annealed	Non magnetic; slight after cold work

Note: design to 205 MPa yield at room temperature, and check code stress tables for any line running above 200 °C.

Equivalent Grades for 317 and 317L SS Pipe

Standard	317	317L
UNS	S31700	S31703
AISI	317	317L
EN / Werkstoff	1.4449	1.4438
EN name	X3CrNiMo18-12-3	X2CrNiMo18-15-4
JIS	SUS 317	SUS 317L
BS	317S16	317S12
AFNOR	n/a	Z3CND19-15-04

SS 317 Pipe Available Sizes and Dimensions

NPS	DN	OD, mm (in)	Sch 5S, mm	Sch 10S, mm	Sch 40S, mm	Sch 80S, mm
1/8	6	10.3 (0.406)	n/a	1.24	1.73	2.41
1/4	8	13.7 (0.539)	n/a	1.65	2.24	3.02
3/8	10	17.1 (0.673)	n/a	1.65	2.31	3.20
1/2	15	21.3 (0.839)	1.65	2.11	2.77	3.73
3/4	20	26.7 (1.051)	1.65	2.11	2.87	3.91
1	25	33.4 (1.315)	1.65	2.77	3.38	4.55
1 1/4	32	42.2 (1.661)	1.65	2.77	3.56	4.85
1 1/2	40	48.3 (1.902)	1.65	2.77	3.68	5.08
2	50	60.3 (2.374)	1.65	2.77	3.91	5.54
2 1/2	65	73.0 (2.874)	2.11	3.05	5.16	7.01
3	80	88.9 (3.500)	2.11	3.05	5.49	7.62
3 1/2	90	101.6 (4.000)	2.11	3.05	5.74	8.08
4	100	114.3 (4.500)	2.11	3.05	6.02	8.56
5	125	141.3 (5.563)	2.77	3.40	6.55	9.53
6	150	168.3 (6.626)	2.77	3.40	7.11	10.97
8	200	219.1 (8.626)	2.77	3.76	8.18	12.70
10	250	273.0 (10.748)	3.40	4.19	9.27	12.70
12	300	323.8 (12.748)	3.96	4.57	9.53	12.70
14	350	355.6 (14.000)	3.96	4.78	9.53	12.70
16	400	406.4 (16.000)	4.19	4.78	9.53	12.70
18	450	457.0 (17.992)	4.19	4.78	9.53	12.70
20	500	508.0 (20.000)	4.78	5.54	9.53	12.70
24	600	610.0 (24.016)	5.54	6.35	9.53	12.70

Rows from NPS 14 upward are marked against B36.19M. Sch 160 and XXS walls follow ASME B36.10M and can be supplied on request.

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Aplication of 317 & 317L Stainless Steel Piping 

317L earns its place where 316L starts to pit and a nickel alloy would be too expensive.

• Flue gas desulphurisation. Scrubber piping that carries chlorides and sulphur acids.
• Pulp and paper. Bleach plant lines exposed to chlorine dioxide and chlorides.
• Chemical and petrochemical plants. Acetic, phosphoric and dilute sulphuric acid service, and condensers.
• Power generation. Condenser tubing and cooling water lines with brackish water.
• Textile and dye works. Hot acid dyeing liquors.
• Food and pharmaceutical processing. Brines and acidic products where 316L is marginal.
• Ink and pigment production. Corrosive pigment slurries.

For still harsher chloride service, compare it with 316L pipe at the lower end and duplex grades at the higher end.

Frequently Asked Questions