Bonnetless globe valves for high pressure superheated service, introduction, features, parts and maintenance

1.    Introduction：

Bonnetless globe valves are used for demanding conditions of operating temperature -196℃~800℃.

The production scope can be referred to as the below table

2. Configuration features

2.1 Structure is based on bonnetless type by thrust ring or threaded body-bonnet connection;

2.2 The valve seat and valve disc sealing surface are all made of cobalt-based carbide plasma spray welding, which has good wear resistance and scratch resistance.

2.3 The surface of the valve stem is treated with anti-corrosion nitriding or quenching and tempering;

2.4 It can be installed in any position of the pipeline.

3． Main part material：

4. Storage and maintenance

4.1 The valve must be kept in the dry and ventilated space. Both sides protected by covers all the time;

4.2 The valve must be checked periodically to eliminate dirt if any and grease the machining faces.;

4.3 After installing, the valve must be examined regularly and repaired timely;

4.4 In case of disassemby repair, the valve must be tested by hydro pressure test after assembly.

5. Installation and commissioning

5.1 Before assembling, check the valve name plate carefully to identify if it suits to the using requirement;

5.2 Examine the cavity and seat and remove the foreign matters inside;

5.3 When assembling , check the flow direction shall conform to the body arrows;

5.4 After for being kept a long time, the valve must be operated testing before using;

5.5 Check butt welds have intact surface and correct welding size.

6. Operation

6.1 During the operation of the globe valve, the force should be stable and not forced. Some parts of the high-pressure globe valve that are opened and closed by force have taken into account that the impact force cannot be equal to that of a general globe valve.

6.2 When the globe valve is fully opened, the handwheel should be reversed a little so that the threads are tightly tightened to avoid loosening and damage.

6.3 When the pipeline is first used, there is a lot of internal dirt, the globe valve can be slightly opened, and the high-speed flow of the medium can be used to flush it away, and then gently close (can not be closed quickly or violently to prevent residual impurities from pinching the seal face), turn it on again, repeat this many times, rinse off the dirt, and then put it into normal work.

6.4 There may be dirt on the sealing surface of the normally open globe valve. When it is closed, it should be washed clean by the above method, and then officially closed.

6.5  During operation, if it is found that the operation is too laborious, the reason should be analyzed. If the packing is too tight, it can be loosened appropriately. If the valve stem is skewed, the personnel should be notified for repair. When some globe valves are closed, the closing member is heated and expanded, which makes it difficult to open; if it must be opened at this time, the bonnet thread can be loosened by half a turn to one turn to eliminate the stress of the valve stem, and then the hand wheel is turned.

7. Trouble-shooting methods