My client is requesting pumps insulation for personal protection for services above 60 C. Where can I find solid arguments against it. It is too expensive.
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.)
You are right, safety first. My concern is mainly, if it is a normal practice to insulate rotary equipment like pumps whit high maintainability requirements.
I think what must be assured is that nobody can (by mistake or accident) come into direct contact with the hot surface. "Hot" because everything above 50 or 55 °C (not sure about the exact value) requires protection against contact. Such a protection does not have to be a capsuled hood or something similar. Perhaps a chain with warning notice around the machine is sufficient or a metal hood over the hot parts. That depends how your machine looks like.
That should not be your question. People can be hurt when touching a hot surface. And your client is requesting a certain protection. It is not common to insulate pumps for 60 °C fluid under a hood but it is not uncommon (and I've seen it) that pumps for hot fluids are barricaded by a chain or something similar and that a warning is attached.
You did not specify the industry involved. We would not normally insulate pumps below about 100 °C unless they were streams that could freeze in winter. Doing so introduces a potential for under-insulation-corrosion. We use primarily API pumps and the vast majority of them are outside, not under roofs or in buildings. Wet insulation can be a problem depending on the materials of construction.