Regarding the issue of holes in the cover
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It was originally specified in the standards that openings on the head had to be located within 80% of the head’s diameter, but this requirement has now been removed. Question: 1. Why was this item removed? 2. Does this original requirement refer to the fact that the entire nozzle connection must be within 80% of the diameter of the head, or does it also mean that the effective reinforcement area of the nozzle must be within 80% of the diameter?
Which standard and which clause are you referring to?
Does no one know? This requirement is no longer included in GB150-98 (it was present in the original GB150-89); any openings on the head must be located within 80% of the diameter of the head
It might be due to the processing method used for the end caps
The section on opening reinforcement in GB150-98 also specifies that when openings are made in the head, and these openings are located more than 80% of the head’s diameter away from its center, the formula for calculating the thickness changes. Let’s check whether the standard indeed states this