Taboo 21

The installation position has no operating space

Measures: Even if the installation is initially challenging, it is important to take into account the operator’s long-term work while positioning the valve for operation. In order to make opening and closing the valve easier, it is advisable to position the valve handwheel so that it is parallel to the chest (usually 1.2 meters away from the operating room floor). To prevent awkward operation, the hand wheel of the landing valve should face upward and not sloped. The wall machine’s valves and other components should allow enough space for the operator to stand. It is quite dangerous to operate on the sky, especially when using acid-base, hazardous media, etc.

Taboo 22

Valves made of impact brittle materials

Measures: When installing and building, exercise caution and stay away from hitting brittle-material valves. Check the valve, specs, and models before installation, and look for any damage, especially to the valve stem. The valve stem is most likely to be skewed during shipping, so turn it a few times to check whether it is. Clean the valve of any debris as well. To avoid damaging the hand wheel or valve stem when lifting the valve, the rope should be fastened to the flange rather than either of these components. The valve’s pipeline connection needs to be cleaned.To remove iron oxide chips, mud sand, welding slag, and other sundries, use compressed air. Large sundries particles, such welding slag, can obstruct small valves and render them inoperable in addition to easily scratching the sealing surface of the valve. In order to prevent buildup in the valve and interference with the medium’s flow, the sealing packing (line hemp plus lead oil or PTFE raw material tape) should be wrapped around the pipe thread before attaching the screw valve. Make sure to evenly and symmetrically tighten the bolts while installing flanged valves.To avoid the valve from producing too much pressure or potentially cracking, the pipe flange and the valve flange need to be parallel and have an appropriate amount of clearance. Brittle materials and low strength valves require special attention. Pipe-welded valves should be spot-welded first, followed by a complete opening of the closing sections, and finally, dead welding.

Taboo 23

The valve has no heat preservation and cold preservation measures

Measures: Some valves are also required to include external protection features for heat and cold preservation. Sometimes a heated steam pipeline is added to the insulation layer. The type of valve that should be kept warm or cold depends on the demands of the manufacturing. In theory, heat preservation or even heat tracing is needed if the medium inside the valve cools too much, which will reduce production efficiency or cause the valve to freeze. Likewise, when the valve is exposed, which is bad for production or results in frost and other undesirable phenomena, the valve needs to be kept cold. Cold insulation materials include cork, perlite, foam, plastic, diatomaceous earth, asbestos, slag wool, glass wool, perlite, diatomaceous earth, etc.

Taboo 24

Steam trap not installed bypass

Measures: Some valves have instruments and bypasses in addition to the basic protection features. For simple trap maintenance, a bypass has been installed. There are more valves placed with bypass. The condition, significance, and production requirements of the valve determine whether a bypass should be installed.

Taboo 25

Packing not replaced regularly

Measures: Some packings for the valves in stock need to be replaced since they are ineffective or inconsistent with the medium being utilized. The stuffing box is always filled with regular packing and the valve is exposed to thousands of various media, however when the valve is in operation, the packing must be customized for the media. Press the packaging in place by going around in circles. Each circle’s seam should be 45 degrees, and the seams of the circles should be 180 degrees apart. The lower portion of the gland should now be compressed to the appropriate depth of the packing chamber, which is typically 10–20% of the packing chamber’s total depth. The height of the packing should take this into account.The seam angle for valves with stringent criteria is 30 degrees. Circle seams differ by 120 degrees from one another. Three rubber O-rings (natural rubber resistant to weak alkali below 60 degrees Celsius, nitrile rubber resistant to oil products below 80 degrees Celsius, and fluorine rubber resistant to various corrosive media below 150 degrees Celsius) can also be used, depending on the circumstances, in addition to the aforementioned fillers. Nylon bowl rings (resistant to ammonia and alkali below 120 degrees Celsius), laminated polytetrafluoroethylene rings (resistant to strong corrosive media below 200 degrees Celsius), and other shaped fillers.Wrap a layer of raw polytetrafluoroethylene tape outside the regular asbestos packaging to enhance sealing and lessen valve stem deterioration from electrochemical action. To keep the area even and keep it from becoming too dead, spin the valve stem while compressing the packing. Do not tilt while you tighten the gland with a consistent effort.