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 Ultra-Supercritical Power-Plant Bolting — Durehete 1055 + Alloy T41 at 600°C+ / 300 bar+
Ultra-supercritical (USC) power plants push HP main steam to 600-620°C and 280-300 bar. The bolting envelope sits at the upper limit of Durehete 1055 service capability; for the hottest USC stages, austenitic stainless or nickel-base bolting from EN 10269 takes over.
USC Service Envelope
USC HP main steam: 600-620°C / 280-300 bar. USC reheat: 600-625°C. Bolting steel selection sits at the upper limit of ferritic Cr-Mo-V-Ti-B capability; austenitic and nickel-base alloys take over above 620°C casing skin temperature.
Durehete 1055 / Alloy T41 Role
For USC casing flanges that run at 565°C casing skin temperature (typical due to insulation losses below the 600°C main steam), Durehete 1055 / Alloy T41 remains the procurement specification. Above 565°C casing skin, escalate to nickel-base bolting (e.g. NiCr20TiAl).
Advanced Ultra-Supercritical (A-USC)
A-USC plants targeting 700°C main steam exceed the Durehete envelope entirely. Bolting selection moves to nickel-base superalloys (Inconel 740H, Haynes 282) covered under EN 10269 nickel-base section and equivalent ASME Section II.
Dual Certification Requirements
USC plants in Germany require VdTÜV Werkstoffblatt 350 alongside EN 10269 type 3.1 / 3.2. Indian and Chinese USC plants typically accept EN 10269 alone or with ASME Section II Part D dual certification.
Frequently Asked Questions
Which Durehete grade is specified for ultra-supercritical power-plant 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 ultra-supercritical power-plant 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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