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 Supercritical Power-Plant Bolting — Durehete 1055 + 950 at 374°C+ / 221 bar+
Supercritical power plants operate above the water critical point: 374°C / 221 bar. Modern supercritical units run main steam at 540-580°C / 240-280 bar. Durehete 1055 (Alloy T41) covers HP casing bolting; Durehete 950 (Alloy T31) covers IP plus subcritical balance-of-plant.
Supercritical vs Subcritical
Subcritical units operate below 221 bar; supercritical units above. The supercritical thermodynamic cycle delivers higher plant efficiency (40+ percent versus 35 percent subcritical) but pushes bolting steels harder. Modern supercritical HP main steam targets 565°C / 250 bar; reheat targets 565-600°C.
HP Casing Bolting
Durehete 1055 / Alloy T41 is the HP casing flange bolt grade for supercritical units at 540-565°C. The Ti+B microalloying covers the 100,000-hour creep-rupture envelope.
IP Casing Bolting
Durehete 950 / Alloy T31 covers IP casing flange bolts at 540°C reheat conditions.
Balance of Plant
LP casing bolting and main-steam stop-valve bolting sit at lower temperature; Durehete 900 / Alloy T22 covers the lower-temperature service. Boiler superheater header bolting follows the HP grade selection.
Frequently Asked Questions
Which Durehete grade is specified for 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 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.
Satisfaction Survey
