One thing not mentioned is the location of the insulated component.
In our case the process runs at temperatures from 200°C-300°C inside a an occupied building and the surface temperature is very relevant to the environmental temperature in the workplace. Not only does the workplace temperature have to be controlled but the usage of the heating media, vaporized oil, has to be considered.
Back in the good old days of asbestos our surface temperature standard was 50°C. This was met with no problem. The lost of asbestos resulted in the change of the surface temperature standard to 59°C. This caused almost immediate problems with the increase in workplace temperatures in some areas to an unacceptable range. There were several problems; not enough vent fans, ambient outside air of 35°C with high humidity and the finite capacity of the process heating source. Because of this the insulation surface temperature max was returned to 50°C or less. This required an increase in the thickness, with a substantial cost of the insulation, form the standard established with Asbestos containing materials. Insulation costs are quite a concern as every piece on each process is different and has to be hand laid up.
In our case the majority of the insulation has to be made removable for a unit overhaul at least once a year. On the few units that were insulated with 59°C surface temperature in mind the handling of the insulation became a problem for the mechanics using the normal PPE. A lot of this insulation instead of being handed off was dropped and destroyed. The small increase in surface temperature required the use of hot gloves and slowed the dismantling of the process piping to point where it became a serious safety concern. Handling of insulating components became a major cost factor with the lost of Asbestos as the normal Calcium Silicate loses most of its strength after a short exposure to 200°C. The process dictates that the piping be dismantled at temperature or allowed to cool to below 185°C. At 185°C the polymer has to be mechanically cut at each flange.
All new insulation on site is now installed with 40°C as standard and the weather covering on any flammable process line be SS. This is SS covering with SS bands. In fact there has been a movement to change the standard covering to SS from AL on all lines.
This is the long way to say that the of a insulation of a particular process or insulation in general should be an engineering exercise taking all things into consideration, not in least the surface temperature required for personnel protection.
Did OSHA ever come out with a requirement for this temperature?
