Insulation for high temperature service flanges

[mthakur]

Dear all,
We have a new discussion ongoing on to a very simple and basic issue in the organization, I would like to have your opinion and suggestions on the subject. Generally all the flange joints of hot sevices such as steam, boiler feed water gas etc are insulated to reduce the heat loss as well to provide personel protection. There is a discussion ongoing whether the flanges for only the gas lines should be kept open. The argument given to support this reason is early detection of leak if it occurs. Also accumulation of gas due to leak in the insulation sheet may create explosive mixture and is potential hazard.

Another argument in this regard is that fastners being the weakest link in a flange joint will be subjected to high temperature due to the insualtion and shoul be kept open.

Keeping the flanges uninsulated for high temperature services pose a potential safety hazard besides loss of energy.

Please suggest what are the practices being followed in other place.

regards.

 

[unclesyd]

The bolting should be designed for the operating temperature of the line and flange so there is no problem with the fasteners. We have areas where the coverings also figures into the fire protection scheme.
All flanges are covered if the temperature is above 140̊F or we have a high freeze point product in the line where tracing is needed. The covering extends to the small steam lines.

S/S lines are not generally covered, we use S/S bolts, unless we are trying to conserve heat or the line is traced. We do use flange shields on S/S flanges.

Most other C/S process flanges are covered as we are near a salt water bay and corrosion is problem. Utility flanges, which are minimized, are not covered with the exception of the Chilled Water system.

We have a huge inside system that operates at 600̊F and everything is covered. Because of the proximity of personnel the skin temp is limited to 120̊F. This does three things it protect the people, conserves energy, and keeps the ambient temperature down.

The natural gas lines are not covered except near the heating oil vporizers.