For large diameter GRP/FRP pipes, it is very expensive to manufacture steel moulds; thus we could also adopt steel structure as the framework and processe GRP /FRPas the surface. This combined structure has the characteris such as simple production and low cost. In China, more than 95% of GRP/FRP pipe manufacturers are using this type of combined GRP/FRP moulds to manufacture qualified GRP pipes in compliance with international standards and export them to the overseas market.