MCT----- Maintenance manual Gate Valve

Gate valves are installed in areas where it is required that the valve be used fully open or fully Closed"

1. INSTALLATION:
For the proper installation of gate valves these steps should be followed:
1.1. Remove all left over particles of rust, slags, dust, and dirt from inside the pipeline.
1.2. Remove protective shields from flanges and stem.
1.3. Proper support of valve and/or pipeline should be provided to eliminate strain and fatigue of end connections. 10
1.4. Although the nuts (114) on the gland bushing flange (20) are adjusted before shipping, we recommend that they be readjusted before installation.
1.5. Make sure that the valve opens and closes correctly.
1.6. Install the valve in closed position and whenever possible with the stem (4) in vertical position.
1.7. Follow the indications on metal identification plate of the valve concerning limits of pressure, temperature and materials.

CAUTION:
Never lift the valve by the handwheel (22) to move it from one place to another.

2. MAINTENANCE:
Gate valves should normally be installed in places where it is not necessary to open or close them frequently. Therefore, they become long lasting and maintenance services are kept to a minimun. Here we show a set of instructions that will be the basic maintenance services that gate valves need:

2.1. LUBRICATION:
2.1.1. POINTS OF LUBRICATION:
2.1.1.1. Bonnet (3) at the level of the stem bushing (15). Applies in all the designs.
2.1.1.2. Bonnet (3) at the level of the lantern (17).
2.1.2. RECOMMENDED SCHEDULE OF LUBRICATION:
The frequency of valve lubrication should be based on user's common sense and experience with the installed equipment. The following indications should be used as a minimum guideline until operating experience indicates otherwise:
2.1.2.1. Minimum once a year.
2.1.2.2. Every three months if the valve is operated infrequently (once a day or less).
2.1.2.3. Every 1000 cycles if the valve is operated more than ten times a day.
2.1.2.4. Every 500 cycles if the valve is used in corrosive or other severe services and operated more than ten times a day.
2.1.3. RECOMMENDED LUBRICANTS:
The type of lubricant to be used will depend upon the service conditions of the valve (temperature, type of fluid, etc.).
CAUTION:
The lubricant will be used to reduce friction in case 2.1.1.1. and as a valve sealer in case 2.1.1.2.
The threads of the stem (6) should be kept lubricated, clean, and dust free. lf the valve is going to stay open for a long period of time, the exposed section of the stem should be protected and the valve should be activated occasionally to prevent excessive torque (specially in pipelines for high temperature fluids and where there is a chance of scale formation or solid sediment accumulation).
2.2. REPLACING THE BODY-BONNET GASKET:
The frequency of change of this gasket (86) will be left to the user's criteria based on his experience with the equipment. Following these steps:
2.2.1. The valve should be in open or semi-open position.
2.2.2. Bleed off the internal pressure of the valve..
2.2.3. Unscrew the stud nuts (111).
2.2.4. Remove the studs (106) that hold together the body (1) and the bonnet (3).
2.2.5. Remove the group of pieces that Include the bonnet (3) and the wedge (4).
2.2.6. Place a new gasket (86). (see note at the end).
2.2.7. Put bonnet (3), studs (106), and stud nuts (111) back on.

2.3. STEM PACKING ADJUSTMENTS:
Stem leaks are most frequently associated with start-ups or other operating changes, but some may develop during steady operation or after long use. Stopping stem leaks on promptly reduces damages to the stem packing (84) and to the valve. To stop stem leaks the following instruction should be followed :
2.3.1. Adjust the nuts (114) on the gland bushing flange (20).
2.3.2. If this does not stop the leak, it means that packing rings (84) (see notes at the end) should be added to the stem (6). For this process follow these ste0 ps:
2.3.2.1. Set valve in fully open position. This will assure that the stem (6) and the back seat (18) are making contact. Right after doing this, the leak should completely stop.
2.3.2.2. Carefully loosen and remove the nuts (114) on the gland bushing flange (20) screwed to the eye bolts (33).
2.3.2.3. Lift the gland bushing flange (20) and the gland bushing (34) and let the first one rest on the edge reserved for this purpose. In this way, there will be access to the stem packing chamber (84).
2.3.2.4. Place the packing rings (84) on the stem (4). As each ring is inserted, it should be compressed by the gland bushing (34) before inserting the next one making sure that the cuts done on them to be able to insert them do not coincide with each other .
2.3.2.5. Put the gland bushing (34), the gland bushing flange (20), the eye bolts (33), and the nuts (114) back on. Make sure the nuts are tightened.
2.3.2.6. Should the leak persist, the valve will have to be repacked and all packing rings (84) should be replaced for new ones. To do this, follow steps 2.3.2.1 through 2.3.2.5 once more

NOTE:
The material and construction of the body-bonnet gasket and the packing rings will depend on the service conditions of the valve. In case of any doubts, please consult us.
3. INSTRUCTIONS TO PRESERVE VALVES DURING STORAGE:
The instructions below should be followed to ensure that the valves are at their best conditions at the moment of installation:
3.1. Store valve(s) in horizontal position.
3.2. If valve(s) is(are) going to be stored for a long period of time, the following directions should be followed every three months approximately:
3.2.1. Operate the valve operator (handwheel,- reductor, or actuator) to make sure that the valve opens and closes correctly.
3.2.2. Clean up bore area from dirt and foreign particles.
3.2.3. Lubricate seats area to protect them from rust, wear, dirt, and other damages.
3.2.4. Replace the protective covers on flanges if damaged.
3.2.5. Wrap stem with plastic or paper. If the stem is going to be exposed keep It lubricated at all times.
3.2.6. If possible, the valves should be stored under roof.
For major maintenance services such as damage to the sealing pieces (wedge and rings) or changes that require disassembling the valve, please consult us.

CAUTION:
The eye bolts (33) and nuts (114) adjusting the gland bushing flange (20) never should be loosened with the valve in closed or semi-open position.

WARNING:
Never disassemble valves under warranty without consulting the manufacturer first, since doing it without the proper authorization can void the warranty.

WARRANTY:
The seller warrants its products against defects in material or workmanship, when used on those applications approved by seller's option of such defective products. The products will have a period of warranty of 12 months under service and 18 months in storage from date of original shipment. The seller's liability under this warranty shall be limited to repair or replacement at seller's option of such defective products.
Any product claimed to be defective must be returned prepaid for inspection. Items showing abusive use, used for purposes other than intended or having been altered in any manner will not be repaired or replaced except at the expense of the user. Products found to be defective by our examination will be repaired or replaced at no expense to the user.