Boiler feed pumps are critical for operations within the power industry. Time savings during installation and removal can save the plant lost hours of generation. SuperboltTM multi-jackbolt tensioners (MJTs) are widely used on this piece of equipment. Often Superbolt tensioners cost less than the replacement OEM nuts as the tensioners for these applications do not have to be made from expensive high temperature alloys.

Challenge: Heating Rods and a large impact wrench (referred to as Big Bertha) were previously used on these 5" diameter nuts. This method of tightening was very time consuming, posed safety hazards, and required use of the overhead crane from the turbine deck. The crane time was particularly valuable during turbine outages. Two men operated the impact while one man operated the crane.

Solution: The installation of MJTs was done using only two workers instead of three. Impacts were used followed by calibrated torque wrenches. The final torque was only 152 ft-lbs per jackbolt. Because the mechanics worked at 180? apart and followed a star pattern around the flange tightening in several steps, the gasket crush was very uniform throughout the procedure.

This was verified by a field service technician from the pump company with feeler gauges. This very large unit has only one boiler feed pump. If the pump should ever require an element change out forcing an unscheduled outage, the time saved removing the MJTs will save generation time. Additionally, should a nut seize on a stud during an emergency element change out, stud removal can take up to 8 hours or more with the previous method. With Superbolt tensioners, the main thread does not slide while under load so thread galling and seizure is eliminated.

The Nord-Lock Group manufactures patented Superbolt MJTs designed to eliminate unsafe and time consuming bolting methods. We offer a unique combination of bolting expertise and wide product range, which also includes multifunctional wedge-locking solutions. With over 30 years of documented success in major industries, the company is a trusted partner in optimisation of bolted connections.

(Nord-Lock Pte Ltd, Singapore. Tel: +65 6515 6658. Fax +65 6515 4485. Email: evan.ang@nord-lock.com)