3LPP and 3LPE 3LPP and 3LPE songkarn (Mechanical) (OP) 4 Oct 15 12:55 Dear sir, Plant specification have specified pipe underground have to coated 3LPP for external surface but contactor request to deviate to 3LPE , so can i accept or not ? Best regards, SK RE: 3LPP and 3LPE Ron (Structural) 4 Oct 15 23:55 That depends on your application. Both are used as pipe coatings; however polyethylene and polypropylene are different materials with somewhat different chemical and physical properties. If you don't know the differences and the conditions that caused one to be specified over the other, then you should not change without further consideration. There was probably a reason someone specified one as opposed to the other, so you need to know that reason or you can't make the decision. Ask the person who specified the 3LPP if that's what he MUST have or is a 3LPE coating acceptable. RE: 3LPP and 3LPE songkarn (Mechanical) (OP) 5 Oct 15 04:06 Dear Ron, Thanks for your reply. SK.