Fusible Plug

PROSPEC Industrial supplies stainless steel fusible plug inserts, which are designed for ease of installation with all tube tees rather than expensive female branch tees. All inserts are made of 316 stainless steel for maximum corrosion resistance, with temperature melting ranges clearly marked on the tube.


  • 3/8″ Outside Diameter x 1.570″ in Length
  • Maximum Bleed Capacity: .250″ Diameter Orifice
  • Maximum Working Pressure: 200 PSI

Additional manufacturer information:

  • The fusible plug shells are manufactured from 316 Stainless Steel and the fusible material is lead, tin, and bismuth which gives the fusible plug to correct eutectic temperature characteristics.
  • In a clean atmosphere using clean air or nitrogen as the control media, there is minimal deterioration and the plugs do not have to be replaced on a maintenance schedule. Salt air atmosphere is considered clean air.
  • The fusible plugs also should be used in areas where the temperature is at least 30 degrees below the rating of the fusible plug to prevent “creep”.
  • A corrosive atmosphere is one in which there is a reaction with the fusible material (lead, tin, and bismuth). Painting the tip of the fusible plug will afford protection against corrosion and will not impact the effectiveness of the material.
  • The working pressure is 50 psi because of safety reasons. The pressure rating is much higher, however, when the eutectic metal starts melting it does not turn immediately to liquid but melts enough to allow the metal plug to be expelled and can be considered a projectile which can cause serious injury.
  • Use of natural gas for the control media is not recommended because the condition of the plug internally cannot be monitored and the chemical composition of natural gas and its affect on the eutectic alloy cannot be predicted.