Visual Inspection and Neutralizing
A visual inspection shall be made when valves are first removed from service. The presence of deposits or corrosion products in the valve and in the piping should be recorded and valves should be cleaned to the extent possible prior to disassembly. Check the condition of external surfaces for any indication of corrosive atmospheric attack or evidence of mechanical damage.
KIASA valves should be disassembled as described below. Parts identification may be found in Figure
1. The parts from each valve should be properly marked and segregated to keep them separate from parts used in other valves.
a. Remove the cap (40) and cap gasket (41). If the valve has a lifting lever device follow the instructions on pages 15.
b. Remove the nozzle ring set screw (4) and set screw gasket (27). Record the position of the nozzle ring (3) with respect to the disc holder (5) by counting the number of notches required to raise the ring until it just touches the disc holder. This information will be needed again when reassembling the valve.
c. Loosen the adjusting bolt nut (25). Before releasing the spring load, make note of the depth of the adjusting bolt in the bonnet and count the number of turns required to remove the spring load. This information will help when reassembling the valve to its approximate original setting.
d. Release all of the spring load by rotating the adjusting bolt (24) in a counterclockwise direction.
e. Remove the bonnet stud nuts (22).
f. Lift the bonnet (20) straight up to clear the spindle (16) and valve spring (18). Exercise care when lifting the bonnet as the spring and spindle will then be free to fall aside.
g. The spring and spring washers (19) can now be lifted off the spindle (16). The spring and spring washers are fitted together and must be kept together as a subassembly. Spring washers are not interchangeable between ends of the spring.
h. Remove the spindle, guide (15), disc holder and disc insert (8). If parts are difficult to remove, due to the presence of corrosive or foreign materials, soaking in a suitable solvent may be required.
i. Remove the spindle from the disc holder.
j. Lift the guide off the disc holder.
k. Disc Insert Removal
l. Remove the nozzle ring (3) from the nozzle (2).
m. Remove the nozzle (2) from the valve body (1) if necessary. Unless the valve seat on the nozzle has been mechanically damaged or shows signs of corrosive attack, it will not be necessary to remove the nozzle. In most cases the nozzle can be reconditioned without removal from the valve body. To remove the nozzle, turn the valve body over taking care not to damage the bonnet studs (21). Turn the nozzle counterclockwise by using the wrench flats on the nozzle flange or a nozzle wrench designed to clamp onto the nozzle flange.
External parts such as the valve body, bonnet and cap should be cleaned by immersion in a bath such as hot Oakite solution or equivalent. These external parts may be cleaned by wire brushing, provided the brushes used do not damage nor contaminate the base metals. Only clean stainless steel brushes should be used on stainless steel components.
The internal parts such as the guide, disc holder, disc insert, nozzle ring and spindle should be cleaned by immersion in a commercial high alkaline detergent. Guiding surfaces on the disc holder and guide may be polished using a fine emery cloth. The other metal parts may be cleaned using acetone or alcohol, then rinsed with clean tap water and dried.
Check all valve parts for wear and corrosion. The valve seats on both the nozzle and disc insert must be examined to determine if they have been damaged. Most often, lapping the valve seats is all that is necessary to restore them to their original condition. If the inspection shows that the valve seats are badly damaged, remachining will be necessary or it may be advisable to replace these parts. When the time element is a factor, it may be advantageous to replace damaged parts from spare parts stock, thereby permitting the replaced part to be checked and reworked at leisure. The valve spring (18) should be inspected for evidence of cracking, pitting or deformation.
The bearing surfaces on the guide and disc holder should be checked for residual product build up and any evidence of scoring. Inspection of valve components is important to ensure proper valve performance. Damaged valve parts must be repaired or replaced.
Reconditioning of Valve Seats
The tightness of a valve and its proper operation depend directly on the condition of the seats. Many pressure relief valve problems are due to eroded or damaged seats. KIASA valves are constructed with a flat metal-to-metal seat. It is important that seating surfaces be properly refurbished by lapping with a flat cast iron lap coated with the correct lapping compound.
• Lapping Procedures
Unless the seats have been badly damaged by dirt or scale, lapping the seating surfaces should restore them to their original condition. Never lap the disc insert against the nozzle. Lap each part separately against a cast-iron lapping block of the proper size. These blocks hold the lapping compound in their surface pores and must be recharged frequently. Lap the block against the seat. Never rotate the block continuously, but use an oscillating motion. Extreme care should be taken throughout to make certain that the seats are kept perfectly flat. If considerable lapping is required, spread a thin coat of medium coarse lapping compound on the block. After lapping with the medium coarse compound, lap again with
a medium-grade compound. Unless much lapping is called for, the first step can be omitted. Next, lap again using a fine grade compound. When all nicks and marks have disappeared remove all the compound from the block and seat. Apply polish compound to another block and lap the seat. As the lapping nears completion only the compound left in the pores of the block should be Present. This should give a very smooth finish. If scratches appear the cause is probably dirty lapping compound. These scratches should be removed by using compound free from foreign material. Disc inserts should be lapped in the same way as nozzles. The disc insert must be removed from the holder before lapping. Before the disc insert is placed back in the holder all foreign material should be removed from both parts. The insert must be free when in the holder. If the disc insert is damaged too badly to be reconditioned by lapping, it should be replaced. Remachining the insert will change critical dimensions, affect the action of the valve and is not recommended.
• Lapping Blocks
Lapping blocks are made of a special grade of annealed cast iron. There is a block for each orifice size. Each block has two perfectly flat working sides and it is essential that they retain this high degree of flatness to produce a truly flat seating surface on either the disc insert or the nozzle.
Before a lapping block is used, it should be checked for flatness and reconditioned after use on a lapping plate. The block should be lapped in a figure eight motion, applying uniform pressure while rotating the lapping block against the plate as shown in Figure 9.
• Lapping Compounds
Experience has proven that medium coarse, medium fine, and polish lapping compounds will properly condition any damaged pressure relief valve seat except where the damage requires remachining. The following lapping compounds or their commercial equivalents are suggested:
• Machining of Nozzle Seats
If machining of the nozzle seat or other major repairs is necessary it is recommended that the valve be returned to a Tyco Valves & Controls facility for repair. All parts must be accurately machined per KIASA specifications. No pressure relief valve will be tight, nor will it operate properly unless all parts are correctly machined. The most satisfactory way to machine a nozzle is to remove it from the valve body. However, it may also be machined while assembled within the valve body.
In any event it is vitally important that the seating surfaces run absolutely true before machining. Machining dimensions for KIASA valves with metal-to-metal nozzle seats are shown in Figure 10 and Table 8. Remove only enough metal to restore the surface to its original condition. Turning to the smoothest possible finish will facilitate lapping. The nozzle must be replaced when minimum face to seat dimension is reached. This critical dimension is shown in Table 8.
• Machining of Disc Insert Seats
When the damage to the disc insert seat is too severe to be removed by lapping, the disc insert may be machined and lapped provided that minimum seat height is maintained (Figure 11 and table 9).
All components should be clean. Before assembling the following parts, lubricate with pure nickel
- Nozzle and body threads
- Nozzle and body sealing surface
- All studs and nut threads
- Spindle and threads
- Set screw threads
- Spring washer bevels
- Adjusting bolt and bonnet threads
- Bonnet pipe plug
- Cap threads
- Dog shaft bearing threads
- Disc holder threads (bellows valves only)
Lubricate the spindle point thrust bearing and disc insert bearing with pure nickel “Never-Seez”. Special attention should be given to the guiding surfaces, bearing surfaces and gasket surfaces to ensure that they are clean, undamaged and ready for assembly. (Figure 12) For parts identification, refer to Figure 1.
a. Before installing the nozzle (2) apply lubricant to the flange surface in contact with the valve body (1) and on the body to nozzle threads. Screw the nozzle (2) into the valve body (1) and tighten with a nozzle wrench.
b. Screw the nozzle ring (3) onto the nozzle (2).
Note: The top of the nozzle ring should be above the nozzle seating surface. For P, Q, R and T Orifice Style JLT, position the nozzle ring per table 2.
c. For bellows valves only, place the disc holder in a vise (larger sizes may require a 3 jaw vise) as shown in Figure 8. Install the tailpiece gasket (29). Screw the bellows assembly onto the disc holder. Tighten with a suitable wrench.
d. Assemble the disc insert (8) and the disc holder (5). (See page 15 for O-ring soft seat assembly) Install the disc insert retention clip (9) onto the disc insert. Install the disc insert into the disc holder. The disc insert should snap into place using hand force only. Safety precautions should be followed whenever heavy parts are being lifted or transported. Dropping disc holder assembly may dislodge the insert.
e. Assemble the disc holder (5) and guide (15) by sliding the guide over the disc holder.
Note: The guide for D and E orifice valves protrudes up into the valve bonnet.
f. Install the two guide gaskets (28), one above and one below the guide.
Note: When assembling bellows valves, the bellows flange eliminates the need for a bottom guide gasket.
g. While holding the top of the disc holder, install the guide into the body. Align the hole of the guide with the body outlet. Once the guide is seated, the disc holder and disc insert can be lowered onto the nozzle.
Note: Lower the nozzle ring below the seats so that it moves freely.
h. Place the spring (18) and washers (19) onto the spindle (16) and assemble the spindle to the disc holder (5) with the spindle cotter pins.
Note: No cotter pins are required in D through K orifice sizes all other orifice sizes use two cotter pins.
i. Lower the bonnet (20) over the spindle and spring assembly onto the bonnet studs (21) in the body. Position the bonnet counter bore on the O.D. of the guide and lower the bonnet onto the guide.
j. Screw the bonnet nuts (22) onto the bonnet studs and tighten down evenly to prevent unnecessary strain and possible misalignment.
k. Screw the adjusting bolt (24) and nut (25) into the top of the bonnet to apply force on the spring. (The original set pressure can be approximated by screwing the adjusting bolt down to the predetermined measurement.)
l. Move the nozzle ring up until it touches the disc holder, then lower it two notches. This is a test stand setting only.
m. Place the set screw gasket (27) onto the set screw (4) and screw the set screw into the body engaging the nozzle ring. The nozzle ring should move back and forth slightly after the set screw is tightened.
n. The valve is now ready for testing. After testing, the following measures should be taken:
- Be sure that adjusting bolt nut (25) is locked.
- Return the nozzle ring to either the original recorded position or to the recommended position shownin Table 1.
- Install the cap or lifting device. See Figure 13 for lifting lever assembly.
- Seal the cap or lifting lever device and nozzle ring set screw to prevent tampering.