Home > Welded Pipes > High-Temperature Service
High-temperature welded pipes are purpose-built for environments where steel must withstand elevated metal temperatures, internal pressure, thermal cycling, and long-duration load exposure. In refinery heaters, reformers, boilers, and thermal power plants, these conditions are normal. Therefore, engineers rely on A691 / A335-equivalent Chrome-Moly welded pipes that provide creep resistance, oxidation stability, and predictable long-term behavior.
These welded pipes are used in main steam lines, superheater/reheater circuits, cracking unit effluent, reformer outlet lines, furnace coils, heater transfer piping, and high-temperature process loops. Their ability to maintain structural integrity under continuous high metal temperature makes them indispensable for thermal-intensive operations.
Chrome-Moly grades such as P11, P22, P5, P9, and P91 respond well to welding, PWHT, and extended high-temperature exposure, making them highly suitable for welded construction in large diameter and long-run high-temperature lines.
High-temperature service typically involves:
A691/A335 equivalent welded pipes are engineered to safely handle all these conditions.
This combination makes welded pipes the optimal solution for high-temperature industrial lines.
High-temperature welded pipes are extensively used in:
Global demand is driven by expansion in refining capacity, power generation needs, and petrochemical modernization.
These welded pipes are selected for their ability to retain strength and performance in the most demanding thermal conditions.
| Application Type | Typical Service Line | Purpose in Operation |
|---|---|---|
| Boiler & Steam Systems | Main steam, hot reheat, interconnecting piping | Sustain pressure + temperature + long-term creep |
| Superheater & Reheater Circuits | Superheater outlets, reheater sections | Resist thermal shock & oxidation at peak temperature |
| Power Plant Piping | HRSG circuits, turbine inlet lines | Maintain structural integrity under continuous heat |
| Refinery Heater Lines | Radiant coils, convection coils, transfer lines | Withstand scaling, sulfidation & hot spots |
| Petrochemical Lines | Reformer outlets, hot effluent | Handle hot gas + hydrogen-rich environments |
| Chemical & Fertilizer Units | Reforming circuits, hot chemical loops | Provide oxidation & corrosion resistance |
| Industrial Heating Systems | Thermal oxidizers, flue gas ducts | Resist distortion & thermal cycling |
| Heat Recovery Systems | Hot gas recovery, waste heat loops | Prevent scaling & dimensional loss |
| Application Parameter | A691 Welded Pipes | A335 Equivalent (Alloy Steel) |
|---|---|---|
| Primary Application | High-temperature, high-pressure pipelines | Super-heated steam & high-temp fluid lines |
| Material Composition | Cr-Mo Alloy Steel | Chrome-Moly Alloy Steel |
| Typical Grades | A691-1.25Cr, 2.25Cr, 5Cr, 9Cr | P11, P22, P5, P9 |
| Manufacturing Process | SAW (Submerged Arc Welded) | Seamless Equivalent Standards (for reference) |
| Operating Temperature Range | 400°C – 650°C | 400°C – 650°C |
| Pressure Capability | High Pressure | High Pressure |
| Best Use Cases | Refinery steam lines, boiler piping, high-temp process loops | Superheated steam lines, heater coils, high-temp headers |
| Weld Heat Treatment | Mandatory PWHT (Post Weld Heat Treatment) | Normalized / Tempered |
| Recommended Coatings | High-temp anti-corrosion coating (optional) | Not applicable (material dependent) |
| Pipe End Types | Bevel End (BE) | BE / PE (Application dependent) |
| Industries Using These Pipes | Refinery, Petrochemical, Power Plants | Thermal Power, Petrochemical, Furnace Lines |
Boiler & Steam System Lines
Used in main steam, hot reheat, and boiler coil piping.
Must handle:
Thermal cycles
Welded pipes offer predictable performance at elevated temperature.
Superheater & Reheater Lines
These are highest-temperature zones.
Critical for:
Microstructural stability
A691/A335 eq. welded pipes maintain strength even in rapid temperature shifts.
Power Plant Piping
HRSG systems, turbine inlets, and steam headers need:
Refinery Heater & Furnace Piping
Exposed to heater flames, radiant/convection heat, and sulfidation.
Chrome-Moly welded pipes resist:
Petrochemical High-Temperature Lines
Reformer & cracking unit lines face:
Severe thermal exposure
Welded Chrome-Moly pipes maintain mechanical strength in these environments.
Chemical & Fertilizer Units
Key lines include:
High-temp chemical loops
Welded pipes resist oxidation and softening under such conditions.
Industrial Heating & Hot Gas Systems
Thermal oxidizers, hot gas ducts, and heater manifolds require:
Heat Recovery & Flue Gas Systems
Applications:
High-temperature ducts
A691/A335 eq. welded pipes offer stability under fluctuating thermal loads.
| Industry | Application |
|---|---|
| Power Plants | Steam circuits, reheaters, HP piping |
| Refineries | Furnace coils, transfer lines |
| Petrochemicals | Reformer outlets & cracking gas systems |
| Chemicals | High-temperature heating loops |
| Fertilizers | Ammonia reforming, gas heating |
| Industrial Heating | Hot gas ducts, thermal oxidizers |
Looking for A691 / A335 equivalent welded pipes for high-temperature service?
52-A, Mulji Thackersi Bldg, Islampura Street, Shop No. 10, Near Alankar Cinema, Mumbai – 400 004
alloy@inoxsteelindia.in, steel@inoxsteelindia.in
+91 9930796690
P11, P22, P5, P9, and P91 (A691 / A335 equivalent).
Yes. PWHT is essential for Chrome-Moly high-temperature welded pipes.
Yes—welded pipes offer excellent creep strength, oxidation resistance, and weld stability.
Yes. P5/P9/P91 welded pipes are specifically used in furnace coil and heater transfer systems.
Applications of Chrome-Moly welded pipes in boilers, furnace coils, reformers, steam lines, and petrochemical heating systems.