1. Insufficient loading using conventional torqueing methods cased warped flanges

2. Leakage between stages due to gap between flanges (known as “smile”)

3. Labor-intensive operations led to over-budgeted turnarounds

4. Contaminants in the steam path

1. Simultaneous tensioning of studs provided precise loading allowing full flange closure

2. Developed sufficient clamping to overcome warping of inner casing

3. Labor hours drastically reduced – turnaround reduced by one month

4. Water-charged hydraulic nuts eliminated contamination concerns

1. Difficult and unpredictable pre-loading of crosshead hex jam nuts using turn-of-the nut method

2. Difficult crosshead alignment

3. Piston rod bending and fatigue failures

4. Piston rod and crosshead slide life

1. Replace original jam nuts with HTN to achieve uniform and predictable pre-loading

2. HTN incorporates spherical washer for ease of alignment

3. Design features prevent piston rod bending and fatigue failures

4. Uniform loading provides longer life piston rod and crosshead slide

1. Torqueing of nuts in a defined sequence resulted in insufficient load leading to the warped flange condition

2. Warped casing from in-service use made closure difficult

3. Long assembly times using traditional torqueing methods

4. Space constraints

1. Improved clamping load and uniformity from hydraulic tensioning successfully closed the warped flange

2. Independent loading easily performed to close gap

3. Reduced assembly time from 2 days to 3 hours

4. Tensioning system with washers fit within existing spot face and tensioned to an installed residual stud stress of 45,000 psi.

1. Non-uniform load distribution using traditional torqueing methods of valve cover assembly

2. Improper gasket sealing

3. Routine valve servicing is time consuming

4. High risk of valve cover studs

1. Custom-designed four-leg tensioner bridge with external tensioners and 3” diameter x 17” long studs to replace hydraulic wrenching tooling

2. Studs incorporate internal tapered threads that mate directly to tapered tensioner puller screws to achieve elongation

3. Tensioners operating in tandem hydraulically stretch studs to achieve a residual 30,000 psi stud stress after relaxation

4. Tensioner bridge allows installation in a tightly nested hex cap nut pattern

5. Achievement of accurate preload quickly with uniform pressure distribution for proper sealing

1. Non-uniform load distribution between casing halves with traditional torqueing methods and multi-jackbolt torque nuts

2. Resulting leak paths and sub-marginal acceptance tests

3. Extended delivery and commissioning times due to numerous adjustments required to achieve clamping uniformity

1. Uniform and repeatable clamping pressure

2. Trouble-free acceptance testing as leak paths are eliminated

3. On-time delivery and start-up

1. Non-uniform load distribution between casing halves with traditional torqueing methods and multi-jackbolt torque nuts

2. Resulting leak paths and sub-marginal acceptance tests

3. Extended delivery and commissioning times due to numerous adjustments required to achieve clamping uniformity

1. Uniform and repeatable clamping pressure

2. Trouble-free acceptance testing as leak paths are eliminated

3. On-time delivery and start-up