Minimum Shims requirement for Pumps as per API-686
Minimum Shims requirement for Pumps as per API-686
(OP)
Dear Experts,
During Pump to motor alignment, we achieved the alignment with just 0.5 mm shims under motor base but Client inspector insists to provide minimum 3 mm shims as per API-686 and Project specs requirement.
Can you advise me the reason behind minimum 3 mm shimming is must even if we achieved the alignment with 0.5 mm ?
During Pump to motor alignment, we achieved the alignment with just 0.5 mm shims under motor base but Client inspector insists to provide minimum 3 mm shims as per API-686 and Project specs requirement.
Can you advise me the reason behind minimum 3 mm shimming is must even if we achieved the alignment with 0.5 mm ?





RE: Minimum Shims requirement for Pumps as per API-686
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Minimum Shims requirement for Pumps as per API-686
Actually I wish to get some technical explanation which can help me to get concession through TQ from client, Machining of Motor pads is the last option.
RE: Minimum Shims requirement for Pumps as per API-686
There would be a +/- 3 mm tolerance or larger, i.e. +5/-3. By only having 0.5 mm of float as your negative tolerance, this may create problems during future alignments for whatever reason. I guess 3mm was decided as a practical number.
RE: Minimum Shims requirement for Pumps as per API-686
What this means is, if you changed a motor, the centre height - underside of mounting pad to motor shaft centre will be the same or less than the existing motor ie, maybe needs more shim. Changing a pump the centre height, underside of mounting pad to pump shaft centre will be the same or more than the existing pump - this means means more shim under the motor to get shaft centres in alignment.
To put it in numbers, a D180 motor centre height is 180 +00 -0.5 mm, I don't have a pump book handy so assuming a pump centre height of 300mm the tolerance would be something like 300 +1.00 -00mm.
However, the code stipulates 3mm and that's it - sorry.
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Minimum Shims requirement for Pumps as per API-686
RE: Minimum Shims requirement for Pumps as per API-686
RE: Minimum Shims requirement for Pumps as per API-686