Should pipelines be completely embedded into thrust blocks?

For unreinforced concrete thrust blocks in bends and tees for pressurized pipelines, it is recommended that the contact surface between the pipelines and concrete thrust blocks should not exceed 45^o from either side of the pipe in the direction of thrust force through the center of pipelines. The reason is to prevent the occurrence of potential cracking arising from the deformation of pipelines under loading condition. If it is necessary to embed the whole section of pipelines into concrete, it is suggested to coat the pipe with a flexible material

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.