Ball Valve

Superbolt® Tensioners have been used on ball valves for many years, however most times the tensioners have been installed all at once during a reinstallation. One major utility approached Superbolt® with a very inventive game plan to reduce the maintenance time for an upcoming outage.

Part of the planned spring outage by the utility was to pull a ball valve off-line to do some turbine work, with minimal down time. The customer’s plan was to have the standard nuts of the ball valve, which require hydraulic tensioners to install and remove, replaced with Superbolt® Tensioners prior to the outage. To accomplish this, the customer purchased (145) 4-1/2” – 8 tpi tensioners approximately 3 months ahead of the scheduled outage and installed them in their spare time over a several month period (2-3 per day) until both sides of the valve were fully outfitted.

During the spring outage 4 workers (2 per side of the valve) removed all the 4-1/2” tensioners in 2-1/2 hours! The estimated time savings over the previous hydraulic method was 2-3 days. Similar time savings was also accomplished on reassembly of the valve.

Since this is a pumped storage facility, the plant sells power at the peak times of the day to supplement its other steam power plants. Therefore it’s essential for the facility to minimize any down time and using Superbolt® products helped accomplish this. The reduction in down time resulted in significant savings.

Also contributing to the time savings was the fact that Superbolt® Tensioners were not only accurate, but repeatable in providing consistent load from stud to stud. Initially, the tension on the studs was monitored with extensometers. After seeing repeatable results with the first few tensioners installed, the remaining studs did not require any further monitoring, unlike the hydraulic method.

 

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  Bolt Stress: 55,000 PSI
  Preload: 813,000 LB
  Jackbolt Torque: 190 ft•lb