The molten joint must be held immobile under force until cooled adequately to develop strength.  The proper cooling times for the joint are dependent on the material, pipe diameter and wall thickness and are established by the pipe manufacturer or by applicable company, local, state, or federal standards.  Allowing proper times under force for cooling prior to removal from the clamps of the machine is important in achieving joint integrity. Any questions,please contact our sales team via email or Whatsapp as below Email: top@welping.cn Whatsapp : 0086-13185061581(Mr.Pan)