Final answer:
Packing glands should only be tightened when they are leaking, to prevent liquidity of fluids. It's important to tighten them incrementally and carefully not to over-tighten to avoid excessive wear and potential damages.
Step-by-step explanation:
You should only tighten packing glands when they are leaking. Packing glands are used in various types of equipment such as pumps and valves to create a tight seal and prevent leakage of fluids. The packing material is compressed to form a seal around a moving shaft or stem.
Over-tightening can cause excessive wear and tear on the shaft and the packing material itself, leading to failure of the component and the need for maintenance or replacement. It's also important to remember that you should never tighten the gland nuts to the point that it starts to bind the shaft or stem. Doing so can prevent proper operation of the machinery and can lead to damage or unsafe conditions.
When it is necessary to tighten a packing gland due to a leak, it should be done carefully and incrementally. The process involves alternating between opposing nuts in a star pattern to ensure even compression of the packing. If the equipment is operating, adjustments should be done slowly to avoid sudden changes in pressure, which can exacerbate the problem. After adjusting, check the leakage rate; a slight leakage may be normal for certain types of packing as it provides lubrication to the shaft.
Remember that regular inspection and maintenance are critical in preventing leaks and ensuring the longevity of your equipment.