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.