Cast Iron P-Trap Adapter

Transition for adapting Cast Iron P-Trap spigot to PE pipe

Where existing Cast Iron P-Traps are connected to PE pipe, a Rubber Ring joint (RRJ) Transition adapter is required to make a leak tight connection. The transition adapter will be either Eccentric or Concentric in design, depending on the PE pipe size connecting to the P-Trap. Eccentric connectors ensure the level invert is maintained and no septic pooling of wastewater or blockage step exists at the joint between the PE and cast iron.

Recommendations for anchoring the RRJ transition socket to the P-Trap / Chamber wall are given below, two possible conditions are considered:

Option 1: Normal Condition - Where there are no significant ground or thermal forces forces acting on the pipe.  The pipe is buried and installation is not in reclaimed land or on a significant slope.

Option 2: Special Condition - Where ground movement is expected, such as installation in reclaimed land, installation on a steep slope, installed above ground or where the pipe is subject to significant thermal forces.

• Option 1: 90% of cases - Pour a simple concrete anchor block around the puddle flange on the adapter, backfill with soil and compact.  Use this method unless special installation conditions given in Option 2 exist.
• Option 2: Special Conditions - Required in reclaimed ground, when Installation gradient is steep, pipe is installed above ground... any situation that transfers significant pulling forces to the RRJ socket. Pour an integrated Corbel with the chamber wall around the adapter.

Existing P-Traps may have non standard dimensions. We recommend confirming the Cast Iron P-Traps spigot OD before ordering the transition, to ensure the transition will fit and seal correctly when installed. installation procedure and submission documents can be downloaded below:

Submission Document Option 1 – Standard Install

Option 1 Installation 

Submission Document Option 2 – Special Condition Install

Option 2 Installation

PE to Cast Iron Transition (P-Trap) / Spigot / Socket / SDR 17

PE100 Single piece transition adapters, machined from Hollow bar with integrated puddle flange and supplied with a BS EN 681-1 NBR (or equivalent) rubber sealing ring. Sockets can be machined to order once the actual Cast Iron spigot diameter is known.

The design of the transition is Eccentric if the ID of the PE pipe (SDR17) and the ID of the CI fitting is greater than 5% difference.  Eccentric design avoids an internal step.

Note: CI P-Traps vary from manufacturer to manufacturer. The OD of the cast iron spigot must be confirmed before ordering.

• Concentric design type
• Eccentric design type