forming a novel double containment polymeric piping assembly by interfitting slidably interfittable polymeric inner pipe components , including a first induction responsive layer therebetween , and slidably interfittable polymeric outer pipe components , preferably including a second induction responsive layer therebetween , to form an inner connection and an outer connection , while causing the inner connection to be axially offset from the outer connection , applying an electrical induction force around the periphery of the outer pipe components , axially aligned with the inner connection but not with said outer connection , and thereby fusing the inner pipe components and the first polymeric layer together , and moving the components relative to said electrical induction force , axially away from the inner connection , and axially aligned with the outer connection , applying an inductive force around the periphery of the outer pipe components , and thereby fusing the outer pipe components and the second polymeric layer together .