Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Durehete in IP (Intermediate-Pressure) Turbine Bolting — Durehete 950 / Alloy T31 at 480-540°C
IP turbine bolting sits between HP and LP in the steam-turbine cycle. IP main steam temperature 480-540°C. Durehete 950 (Alloy T31 / 40CrMoV4-6 / EN 10269) is the standard specification — the Cr-Mo-V chemistry without Ti+B is sufficient for the IP service envelope and reduces mill cost versus the upgrade to Durehete 1055.
IP Service Envelope
IP main steam temperature: 480-540°C (often 540°C on reheat-cycle units). IP main steam pressure: 30-60 bar after the reheat. Casing flange bolts see the same combined preload-plus-thermal-cycle loading as HP, but at a lower envelope.
Why Alloy T31
The Ti+B microalloying in Alloy T41 (1055) is not required at 540°C maximum service. Plain Cr-Mo-V chemistry in Alloy T31 (40CrMoV4-6 / Durehete 950) covers the IP envelope through 100,000 hours. Specifying T31 rather than T41 saves on mill cost without sacrificing the design margin.
ASTM A193 B16 Cross-Reference
For US procurement specifications that call out ASTM A193 Grade B16, Durehete 950 / Alloy T31 is the direct dual-certification candidate. Chemistry envelopes overlap; heat-treatment cycle is identical. TorqBolt supplies dual EN 10269 + A193 B16 certificates from the same heat.
Bolt Size Range
IP casing flange bolts typically M30 to M80 thread, length 150-900 mm.
Frequently Asked Questions
Which Durehete grade is specified for ip (intermediate-pressure) turbine bolting?
The grade depends on service temperature. Durehete 1055 (T41 / 1.7729) covers up to 565 degrees Celsius; Durehete 950 (T31 / 1.7711) covers up to 540 degrees Celsius; Durehete 900 (T22 / 42CrMoV5-6) covers up to 500 degrees Celsius.
What standard governs ip (intermediate-pressure) turbine bolting?
EN 10269 is the controlling European bolting-steel standard. ASTM A193 Grade B16 is the closest US equivalent for the lower-temperature grades (Durehete 950 and 900).
Are dual certificates available?
Yes. TorqBolt supplies the Durehete grades with EN 10269 type 3.1 / 3.2 inspection certificates plus ASTM A193 dual certification when the procurement specification requires it.
What is the typical lead time?
Lead time depends on size and quantity. Stock sizes ship within a week; custom-machined fasteners run 4-8 weeks from heat traceability through to delivery.
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