Name: China DIN17175 ST35.8 Seamless Steel Pipe Manufacturers Suppliers Factory - Shenzhoutong Steel Pipe
Brand: Shenzhoutong
SKU: 308820115

Item	Details
Executive Standard	DIN 17175 (Seamless steel tubes for elevated temperature service)
Material Grade	ST35.8, Material No. 1.0305
Production Process	Hot Rolled Seamless / Cold Drawn Seamless
Delivery Condition	Normalized (NBK +N), full-length heat treatment
Cross Section	Round seamless tube
Working Temp. Range	-20℃ ~ 450℃ (max short-term peak 600℃)
Max Working Pressure	≤5.88 MPa medium pressure system
Equivalent Grades	EN: P235GH; ASTM: A179 Gr.A; JIS: STB340; BS: CFS320Made-in-Ch...

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DIN 17175 ST35.8 is a German standard non-alloy carbon seamless steel tube specially designed for medium & high temperature, medium-pressure service up to 450℃. It features stable high-temperature mechanical performance, excellent weldability, uniform wall thickness and tight dimensional tolerance, widely adopted in European boiler, power plant, petrochemical and heat exchange systems.

Manufactured via hot rolling / cold drawing seamless process, fully normalized heat-treated to meet DIN 17175 elevated temperature specification. Suitable for steam pipelines, boiler heating surfaces, heat exchangers and pressure piping under long-term thermal load.

Technical Data

Chemical Composition (Weight %, Max Limits)

Element	C	Si	Mn	P	S	Cr / Mo
ST35.8	≤0.17	0.10–0.35	0.40–0.80	≤0.030	≤0.030	No addition

Room Temperature Mechanical Properties

Property	Value
Tensile Strength Rm	360 – 480 MPa
Yield Strength Re (WT ≤16mm)	≥235 MPa
Yield Strength Re (WT 16–40mm)	≥225 MPa
Elongation A (L=5.65√S)	≥25%
Hardness	≤143 HB

Outer Diameter (OD): 14 mm – 711 mm

Wall Thickness (WT): 2 mm – 60 mm

Length: Random length (3–12m), fixed cut length (6m / 9m / 12m / 24m) as customized

Custom small precision sizes (12.7mm OD upwards) available for heat exchanger tubes

Dimensional Tolerance

Outer Diameter: ±0.8% OD

Wall Thickness:

WT ≤ 0.11×OD: ±12.5% nominal wall

WT > 0.11×OD: ±10% nominal wall

Length: ±50mm for fixed lengths

*Surface & End Treatment

Surface Finish: Black hot rolled oxide / Pickled & Annealed (AP) / Bright annealed (BA)

Pipe End: Plain end / Beveled end for welding; plastic caps for anti-damage

Anti-rust: Surface oil coating for seaworthy transport

*Standard Inspection Items

All pipes pass full batch inspection before shipment:
Chemical composition spectroscopy test
Tensile test, low-temperature impact test
Ring expansion / flattening test
100% Ultrasonic Testing (UT) for internal defects
Hydrostatic leak test (no leakage)
Full dimensional measurement
Visual surface inspection (no crack, fold, lamination)
Batch marking & traceability test

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Applications

ST35.8 DIN17175 tubes are core pressure piping materials for medium-high temperature thermal systems, widely used across global industries:

1.Power Plant & Boiler Industry
Low/medium pressure boiler heating tubes, boiler riser tubes, economizer tubes, steam collection headers, auxiliary steam pipelines for thermal power stations.
2.Heat Exchanger & Thermal Equipment
Shell & tube heat exchangers, air preheaters, oil cooling coils, industrial furnace heat transfer pipes.
3.Petrochemical & Fertilizer Plant
Medium-temperature medium-pressure process pipelines, crude oil preheating tubes, fertilizer reaction furnace auxiliary piping.
4.Industrial Heating & Central Heating System
Factory steam transmission lines, district heating high-temperature water pipelines, thermal oil circulation pipes.
6.Machinery & Pressure Vessel Manufacturing
Pressure vessel connecting pipes, hydraulic thermal oil piping, engine high-temperature cooling pipelines.
7.European Engineering & EPC Projects
Compliant with German DIN & EU PED standard, widely supplied to Spain, Germany, Italy, Poland and other EU industrial projects.

Frequently Asked Questions (FAQ)

Q1: What is the difference between ST35.8 and ST45.8 under DIN17175?
A: ST35.8 is low-carbon grade with better ductility, elongation ≥25%, suitable for bending and complex heat exchanger coils under ≤450℃. ST45.8 has higher tensile strength (410–530MPa) for higher pressure load, lower elongation (≥21%). ST35.8 is the mainstream choice for general medium-temperature boiler tubes.
Q2: Can ST35.8 replace ASTM A179 tube directly?
A: Yes, they are equivalent performance grades. ST35.8 complies with DIN pressure standard, while A179 follows US boiler standard. For EU market, ST35.8 is preferred to meet local PED certification requirements.
Q3: What is the maximum sustainable working temperature for ST35.8?
A: Continuous long-term service temperature ≤450℃; short-term instantaneous peak temperature can reach up to 600℃, not recommended for long-term operation above 450℃.
Q4: What certificates can you provide for export?
A: We supply Mill Test Certificate EN 10204 3.1 / 3.2, SGS inspection report, CE marking (PED 2014/68/EU), ISO 9001 factory certification, third-party BV/VERITAS inspection as customer requested.
Q5: What minimum order quantity do you accept?
A: Standard MOQ: 1 metric ton; small trial orders ≥500kg acceptable for precision thin-wall heat exchanger tubes. Mixed sizes in one shipment are supported.
Q6: Is post-processing service available?
A: Yes, we provide pipe cutting, bending, U-bending for heat exchangers, bevel machining, anti-corrosion coating (3LPE) and customized length cutting.
Q7: What heat treatment status do ST35.8 tubes deliver?
A: All tubes are delivered in normalized (NBK) state as mandatory DIN 17175 requirement, eliminating internal stress and stabilizing high-temperature performance. Cold-drawn tubes without normalization are not allowed for pressure service.
Q8: How long is your production & delivery lead time?
A: Standard stock sizes: 7–10 days; customized non-standard OD/WT: 20–30 days; bulk order above 100 tons: negotiable production schedule.