SS 347H Seamless Pipes Manufacturer and Supplier

Stainless Steel 347H Seamless (SML) Pipe is a niobium-stabilised austenitic stainless steel conduit manufactured under ASTM A312 / ASME SA-312, designated as TP347H (UNS S34709). The alloy contains 17.0-19.0% chromium, 9.0-13.0% nickel, and a controlled carbon range of 0.04-0.10%. Niobium (also called columbium) is the key stabilising element. It binds with carbon to form niobium carbides, which prevent harmful chromium carbide precipitation along grain boundaries. This mechanism gives the grade its resistance to intergranular corrosion at elevated temperatures up to 1500°F (816°C).

Minimum tensile strength is 75 ksi (515 MPa), with yield strength of 30 ksi (205 MPa) and elongation of 35% in 50 mm. The "H" suffix signals a higher carbon content than standard 347, and the extra carbon directly improves creep and stress rupture performance during prolonged high-temperature service.

Sachiya Steel International is a manufacturer, supplier, and exporter of Stainless Steel 347H Seamless Pipe in Mumbai, India. With over 2 decades of experience, we maintain a ready inventory of 1,500 to 2,000 metric tons. Available sizes are 1/2" NB to 24" NB (6.00 mm to 610 mm OD) across schedules SCH 5S through SCH XXS.

Every pipe ships with Mill Test Certificates per EN 10204 3.1, and our facility holds ISO 9001, ISO 14001, and ISO 45001 certifications. We supply SS 347H seamless pipe to petrochemical refineries, power generation plants, heat exchanger fabricators, and chemical processing units worldwide.
This page covers:

Specifications
Pricing
Chemical Composition
Mechanical Properties
Equivalent Grades
Industrial Applications
Shipping and Packaging
Frequently Asked Questions

Stainless Steel 347H Seamless Pipe Specifications

The table below lists the standard specification parameters for ASTM A312 TP347H seamless pipe as supplied by Sachiya Steel International.

Parameter	Value
Standard	ASTM A312 / ASME SA-312
Size / OD	1/2" NB to 24" NB (6.00 mm to 610 mm OD)
Wall Thickness / Schedule	SCH 5S, SCH 10S, SCH 20, SCH 30, SCH 40, SCH 80, SCH 120, SCH 140, SCH 160, SCH XXS
Length	Single Random, Double Random, Cut Length (up to 6 metres; custom lengths as per client specification)
End Type	Plain End, Beveled End, Threaded
Finish	Annealed and Pickled, Bright Annealed
Form	Seamless
Dimensional Standard	ANSI/ASME B36.19M, ANSI/ASME B36.10M
Delivery Condition	Annealed and Pickled, Cold Drawn, Bright Annealed

Stainless Steel 347H Seamless Pipe Sizes

Stainless Steel 347H seamless pipes are available in many sizes, schedules, and length options to meet high-temperature and critical process requirements across industries.

Parameter	Details
Product	Stainless Steel 347H Seamless Pipes
Nominal Bore (NB) Range	1/2" NB to 24" NB
Outer Diameter (OD)	6.00 mm to 610 mm
Wall Thickness	0.4 mm to 30 mm (depending on schedule)
Pipe Schedules	SCH 5S, SCH 10S, SCH 20, SCH 30, SCH 40/STD, SCH 80/XS, SCH 120, SCH 140, SCH 160, SCH XXS
Standard Lengths	Single Random (5-7 meters), Double Random (9-12 meters)
Custom Lengths	Available as per client specification

Stainless Steel 347H Seamless Pipe Price

SS 347H seamless pipe price starts from approximately ₹200/kg in the Indian market. Final pricing depends on outside diameter, wall thickness, schedule, length, quantity, and surface finish. Nickel and chromium spot rates also influence the landed cost. Contact us for a current quote.

Stainless Steel 347H Seamless Pipe Chemical Composition

Grade 347H (UNS S34709) is an austenitic stainless steel with controlled higher carbon and niobium stabilisation. The composition per ASTM A312 is listed below.

CarbonC

0.04-0.10%

ManganeseMn

2.00% max

PhosphorusP

0.045% max

SulfurS

0.030% max

SiliconSi

1.00% max

ChromiumCr

17.0-19.0%

NickelNi

9.0-13.0%

NiobiumNb

8xC min, 1.00% max

Stainless Steel 347H Seamless Pipe Mechanical Properties

ASTM A312 TP347H seamless pipe meets the following minimum mechanical requirements, which govern pressure rating calculations and high-temperature piping design.

75 / 515

ksi / MPa (min)

Tensile Strength

30 / 205

ksi / MPa (min)

Yield Strength

35%

in 50 mm

Elongation

201

HB (max)

Hardness (Brinell)

Property	Value
Tensile Strength (min)	75 ksi / 515 MPa
Yield Strength 0.2% Offset (min)	30 ksi / 205 MPa
Elongation (min)	35% in 50 mm
Hardness (max)	201 HB (Brinell)
Hardness (max)	95 HRB (Rockwell B)

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Stainless Steel 347H Equivalent Grades

Alloy 347H is recognised under multiple international designations. The table below covers UNS S34709 across regional standards for cross-referencing project specifications.

Country / Standard	Designation
USA (UNS)	UNS S34709
Europe (EN)	X7CrNiNb18-10
Europe (W.Nr)	1.4961
Japan (JIS)	SUS 347H
France (AFNOR)	Z6CNNb18-10
China (GB)	0Cr18Ni11Nb

Stainless Steel 347H Seamless Pipe Industrial Applications

347H SS seamless pipe serves 4 primary industry sectors: petrochemical refining, power generation, heat exchange systems, and chemical processing.

Petrochemical and Refinery Piping

Refineries specify Type 347H seamless pipe for furnace tubes, transfer lines, and catalytic reformer piping where operating temperatures regularly exceed 1000°F (538°C).

Power Generation and High-Pressure Steam Service

Grade 347H seamless pipe is specified for superheater tubes, main steam lines, and boiler piping in coal-fired and combined-cycle power plants.

Heat Exchangers and Condensers

Stainless Steel 347H seamless pipe is used in shell-and-tube heat exchangers and condensers handling high-temperature process streams.

Chemical Processing

Chemical plants use this in reactor vessels, distillation columns, and process piping exposed to organic acids and oxidising media at elevated temperatures. It is also suitable for concentrated solar power thermal storage systems.

Stainless Steel 347H Seamless Pipe Shipping & Packaging

Heavy-duty wooden boxes Packing

Export Packaging Standard

We strictly follow seaworthy export handling standards to protect SS 347H seamless pipe from transit damage, moisture ingress, and surface contamination during long-distance dispatch.

Heavy-duty wooden boxes with moisture barrier lining
HDPE stretch film wrapping on all bundles
Plastic end caps on threaded and plain-end pipes
Silica gel desiccants to minimize moisture exposure
ISPM-15 fumigated wooden packaging for export

Pipe Bundle Yard Staging

Container End-Cap Protection

Wrapped Export-Ready Bundles

We Export Worldwide

Sachiya Steel International supplies stainless steel products to major industrial markets across North America, Europe, the Middle East, Asia and Africa with export-ready documentation and logistics support.

USA
Canada

Frequently Asked Questions — SS 347H Seamless Pipe

What is the Difference between SS 347 and 347H Seamless Pipe? +

SS 347H has a controlled carbon range of 0.04–0.10%, while standard stainless steel 347 allows up to 0.08% max with no minimum. That higher carbon floor gives 347H better creep strength and stress rupture properties above 1000°F (538°C). Both grades are stabilised with niobium under ASTM A312.

What Sizes are Available for ASTM A312 TP347H Seamless Pipe? +

TP347H seamless pipe is stocked from 1/2" NB to 24" NB (OD 6.00 mm to 610 mm) in schedules SCH 5S through SCH XXS. Single random, double random, and custom-cut lengths are available.

What is the Price of Stainless Steel 347H Seamless Pipe Per Kg? +

SS 347H seamless pipe price starts from approximately ₹200/kg in India. The final rate varies with OD, wall thickness, schedule, quantity, finish, and prevailing market conditions. Contact us for current pricing.

What is the Maximum Operating Temperature for 347H Seamless Pipe? +

Grade 347H seamless pipe is suitable for continuous service up to approximately 1500°F (816°C). Niobium stabilisation maintains creep strength and corrosion resistance across this temperature range.

Can SS 347H Seamless Pipe be Welded On-Site? +

Yes. SS 347H has excellent weldability with all standard fusion and resistance welding methods. Post-weld annealing isn't required under normal conditions, because niobium stabilisation prevents carbide precipitation in the heat-affected zone.

Why is 347H Seamless Pipe Preferred Over 304 for High-Temperature Piping? +

347H provides higher creep and stress rupture properties than 304 or 304L. Unstabilised grades like 304 are vulnerable to intergranular corrosion in the 800–1500°F sensitisation range. The niobium in 347H eliminates that risk.

What Schedules are Available for TP347H Seamless Pipe? +

TP347H seamless pipe is available in SCH 5S, SCH 10S, SCH 20, SCH 30, SCH 40, SCH 80, SCH 120, SCH 140, SCH 160, and SCH XXS. Custom wall thicknesses can be arranged on request.

What Certifications come with SS 347H Seamless Pipe? +

We supply every SS 347H seamless pipe order with Mill Test Certificates per EN 10204 3.1/3.2, PMI test reports, and complete chemical and mechanical test documentation. Third-party inspection (including destructive and non-destructive testing) is available on request.