The Nord-Lock Group’s purpose-built 4WJ solution, executed on your unit by a Boltight-equipped TFA crew. Stop losing combustion air, fuel efficiency and emissions margin.
Request a Quote — 501F 4WJ
Fixed-price within 1 business day
When a 501F was new from Westinghouse, its compressor, combustor and turbine cylinders were perfectly aligned, the flange faces were flush and the 4-Way Joint sealed without intervention.
After years of thermal cycling, maintenance disassembly and varying tensioning practices, the cylinders warp. The upper-half spigot fit gets removed for independent cylinder access — and never gets back to original. Misalignment opens the bolt holes, the flange surfaces no longer mate, and the 4-Way Joint starts leaking combustion air.
The result: lost capacity, degraded heat rate, emissions excursions, and joint surfaces that get worse every cycle.
In 2017, Nord-Lock Group partnered with a 501F operator to engineer a permanent fix. Seven revisions later, the solution is fielded across multiple combined-cycle plants in the US. It combines four mechanical innovations:
A hydraulic manifold supplied by a single 1500-bar pump pressurizes 5 vertical and 5 horizontal bolt locations on each side of the cylinder simultaneously. The cylinder is “squeezed” around the 4-Way Joint to ensure uniform tensioning.
While hydraulic tension is held, Superbolt helicoil bolts and reaction nuts are installed. The MJT breaks high preload requirements into manageable jackbolt torques. Tension is never released at the 4WJ during installation.
An eccentric-pin Cam Bolt that corrects misalignment after the cylinder is “squeezed”. The tool can close internal gaps by .010″ to .015″, ensuring the smallest possible flange-to-flange contact.
A two-piece 90-degree segmented internal seal with bridge seal at TDC, captured by 7 adjustable retainers welded to the case. The seal grows and contracts with operating temperature while keeping combustion air away from the 4-Way Joint.
A typical 501F 4WJ NEW INSTALLATION executed by Giman:
Crew: 4 TFA technicians on-site · Mobilization: 48–72 hours from Laredo, TX
Plant configurations served: combined cycle, peaker, cogen with 501F prime mover.
The R7 solution is engineered to seal across operating cycles. Field experience across multiple US combined-cycle units shows sustained sealing through the inspection interval, provided the unit is reassembled per the published procedure.
Yes — the procedure starts before the cylinder is reinstalled. Plan the 4WJ scope into the existing casing-off window.
Yes. The 2nd-generation soft seal products replace the 3-piece sealing washers and can be applied during your next reassembly.
All consumables and tooling are supplied through our service. You receive a single fixed-price quote covering labor, equipment and consumables.
Cylinder removal/reinstallation, crane services and overall outage coordination remain with your prime contractor. Our scope is the 4WJ solution itself.
