Insulation question

I have a single-pipe steam system with hinged fiberglass insulation covering the pipes. Most of the elbows and tees are insulated and covered with PVC fittings. I have about 8 fittings that are uninsulated, but I do have the PVC covers for these. I do not have any insulation batts for wrapping them before installing the cover. Can I use a standard fiberglass insulation made for wall insulation for these remaining 8 fittings before wrapping them with the PVC fittings? I do not know whether the wall insulation is rated for the temperature of steam pipes. Thank you.