Factory Mutual (FM) Approved

Design Flow™ RED

Factory Mutual (FM) Approved for Fire Protection


Factory Mutual Global (FM) insures and protects the lives, property, and continuity of operation for its insured, by mitigating fire risk. One component of that risk minimization is the rigorous testing of fire protection system components, which includes underground pipe and fittings. Factory Mutual Research Corp. is the FM Nationally Recognized Testing Laboratory (NRTL) which conducts pipe and fittings testing for FM Global Insc. Fire protection system components are rigorously tested to ensure that all approved products pass the aggressive level of FM performance, efficiency and quality requirements. Every GF product labeled with the Factory Mutual (FM) symbol has met the strenuous requirements for fire protection systems. The GF manufacturing processes and the in-house testing have been audited, approved, and bi-annually inspected by Factory Mutual Global, to assure product conformance and performance for the Owner’s security and peace of mind, now, and into the future.

Product Overview

Technical Data:

Size Range:

  • 2" - 24" IPS & DPS

 Pressure Rating:

  • Class 200 (200 PSI) @ 73°F
  • Class 250 (250 PSI) @ 73°F
  • SDR 335 (335 PSI) @ 73°F

Operating Temperature:

  • -50°C to 60°C (-58°F to 140°F)

Joining Technology:

  • IR Plus Fusion
  • Butt Fusion
  • Electrofusion

Standard Ratings:

  • NSF 61
  • FM 1613
  • AWWA C906


  • PE 4710/PE 100

Fields of Application:

  • Fire Mains
  • Chilled Water
  • Process Cooling Water
  • Industrial Water Treatment
  • Bulk Water Distribution
  • Pharmaceutical Manufacturing
  • Pulp and Paper Manufacturing
  • HVAC
  • Power Generation


  • Robust mechanical strength
  • High impact resistance at very low temperatures
  • Good abrasion resistance
  • High chemical resistance
  • Ease of installation
  • Low wegiht
  • Excellent cost to performance ratio
  • Safely and securely joined by heat fusion
  • Corrosion-resistant


System Specification: Factory Mutual Approved Pipe and Fittings Model

NOTICE: This document is intended as assistance and as a guide to support the design of fire protection piping systems. However, it shall not be used as a substitute for the advice of a professional engineer to owners. GF has taken reasonable effort to ensure the accuracy of this sample specification document, but it does not provide all necessary information, particularly with respect to custom or unusual installations. No warranty or guarantee of piping installations is expressed nor implied. This sample specification is not intended to provid

1. General Terms and Conditions

1.1 Scope

  • This specification covers Factory Mutual (FM) Approved and listed high-density polyethylene piping for underground fire main use, made in accordance with the specification requirements of FM. All work shall be performed in accordance with these specifications. http://www.fmglobal.com/assets/pdf/fmapprovals/1613.pdf 

1.2 Engineered and Approved Plans

  • Underground fire main construction shall be performed in accordance with engineered construction plans for the work prepared under the direction of a Professional Engineer. Guidance for polyethylene pipe design and construction is provided in the Plastic Pipe Institute’s “Handbook of Polyethylene Pipe”, available at : http://www.plasticpipe.org/publications/pe-handbook.html

1.3 Referenced Standards

  • Where all or part of a NSF, AWWA, ASTM, FM, NFPA, etc., standard specification is incorporated by reference in this document, the reference standard shall be the latest edition and revision.

1.4 Licenses and Permits

  • A licensed and bonded contractor shall perform all underground fire main construction work. The contractor shall secure all necessary permits before commencing construction.

1.5 Inspections

  • All work shall be inspected by an authorized representative of the owner who shall have the authority to halt construction if, in his opinion, these specifications or standard construction practices are not being followed. Whenever any portion of these specifications is violated, the project engineer or his authorized representative shall, by written notice, order further construction to cease until all deficiencies are corrected. A copy of the order shall be filed with the contractor’s license application for future review. If the deficiencies are not corrected, performance shall be required of the contractor’s surety.

2. Polyethylene Pipe and Fittings

2.1 Qualification of Manufacturers

  • The manufacturer shall have manufacturing facilities and a quality assurance program that are FM Approved as being capable of producing and assuring the quality of the pipe and fittings required by these specifications. The manufacturer’s production facilities shall be open for inspection by the customer or his authorized representative. The project engineer shall approve qualified manufacturers.

2.2 Approved Manufacturers

  • Manufacturers qualified and approved by the project engineer are listed below. Products from unapproved manufacturers are prohibited. Georg Fischer Central Plastics LLC www.gfcp.com GF Piping Systems (Global)

2.3 Materials

  • Materials used for the manufacture of polyethylene pipe and fittings shall be USA PE 4710 high density polyethylene meeting ASTM D3350 cell classification 445574C for black or 445574E for color stripes, and shall be listed in PPI (Plastics Pipe Institute) TR-4 with a standard grade HDB rating of 1600 psi at 73°F. This pipe grade HDPE material meets and exceeds the minimum 76 Industrial PE Technical Handbook 2016 performance requirements of PE3608 material, and is accepted and approved by FM for use in Class 150, Class 200, and Class 267 pipe and fittings.

2.3.1 Potable Water

  • When the main provides firewater and potable water service, the material shall also be listed and approved for potable water in accordance with AWWA C901 and AWWA C906.

2.4 Interchangeability of Pipe and Fittings

  • The FM Approved manufacturer who is qualified and approved by the project engineer shall supply both polyethylene pipe and fittings. Products from non-approved manufacturers are prohibited. In the event of an emergency, pipe and fittings from different manufacturers may be used if authorized by the engineer of record, if both are FM Approved and listed, and if both have the same FM Approved ASTM material designation and material cell classification.

2.5 Polyethylene Pipe

  • Fire main pipe shall be FM Approved Class 150, Class 200, or Class 267 IPS and/or DIPS OD- size polyethylene pipe, and shall be marked with the authorized FM Approved logo. Each production lot of material or pipe shall be tested for melt index, density, and percent carbon-black concentration. Each production lot of pipe shall be tested for dimensions and ring tensile strength. The Pipe shall be produced, inspected, and tested IAW AWWA C901 and AWWA C906.

2.5.1 Service Identification Stripes

  • FM Approved pipe surface may be provided as all black, or black with red stripes. Permanent identification of the striping shall be provided by co-extruding at least 4 color stripes into the pipe outside surface. The striping material shall be the same material as the pipe material except for color. IPS & DIPS sized pipes shall have four equally spaced, longitudinal color stripes. Except as provided in 2.5.2, the optional stripe color shall be red.

2.5.2 Potable Water and Fire Main Pipe

  • Dual-certified potable water and fire main pipe shall be FM Approved and AWWA approved, with an all-black surface or as black with 4 blue stripes.

2.6 Polyethylene Fittings

  • Polyethylene fittings can be molded or fabricated. The fittings manufacturer shall be FM Approved. Each fittings shall be marked with the authorized FM Approval logo. Molded Fittings shall be provided by Georg Fischer-Central Plastics,LLC. Fabricated fittings shall be provided by Georg Fischer Central Plastics LLC, an FM Approved fabrication manufacturer.

2.6.1 Polyethylene Flange Adapters

  • Flange adapters shall be FM Approved and shall be marked with the authorized FM Approval logo. Flange adapters shall have sufficient through-bore length to be clamped in the butt fusion joining machine without the use of a stub-end holder. Flange Adapters shall be joined in accordance with the guidance of the Plastic Pipe Institute Technical Note #38: http://www.plasticpipe. org/pdf/tn-38_bolt_torque_flanged_joints.pdf

2.6.2 Back-up Rings & Flange Bolts

  • Class 150, Class 200 and Class 267 flange adapters shall be fitted with FM Approved Bolt Rings. Flange bolts and nuts shall be grade 3 or higher. Anodic corrosion protection of bolts should be considered for buried flange installations. http://marswater. com/PDFs/SpecSheets/ZincCaps.pdf

2.6.3 MJ Adapters MJ

  • Adapters of each pressure class shall be FM Approved and shall be marked with the authorized FM Approval logo. MJ Gland Rings shall be the C110 heavy Duty style, with all bolts evenly torqued to a range of 60-90 ft-lbs, per AWWA C600.

2.7 Compliance Tests

  • In case of conflict with manufacturer’s certifications, the contractor, project engineer or customer may request retesting by the manufacturer or have retests performed by an outside testing service. All retesting shall be at the requestor’s expense and shall be performed in accordance with these specifications.

3. Joining

3.1 Heat Fusion Joining

  • Joints between plain end pipes and fittings shall be made by butt fusion using only procedures that are recommended by the pipe and fitting manufacturer. The contractor shall ensure that persons making heat fusion joints have received training in the manufacturer’s recommended procedure. The contractor shall maintain records of trained personnel and shall certify that training was received not more than 12 months prior to construction. External and internal beads do not need to be removed.

3.2 Heat Fusion Training Assistance

  • Upon request and at the requestor’s expense, training personnel from the manufacturer or his representative shall be made available.

3.2.1 Butt Fusion of Unlike Wall Thickness

  • Butt fusion shall be performed between pipe ends, or, between pipe ends and fitting spigots having the same outside diameter and pressure class. Butt fusion joining between ends differing by one SDR is permitted, however, the system pressure rating retains the lowest rated component’s pressure class. Transitions between Class 150, Class 200 and Class 267 shall be made with approved flange connections, transition fittings, or MJs.

3.3 Mechanical Joining

  • Polyethylene pipe and fittings may be joined together or to other materials by means of FM Approved flange adapters and back-up rings or FM Approved MJ adapters, or listed Transition Fittings. Where FM Approved pipe or fittings are connected to the socket of Di mechanical joint pipe, fittings or appurtenances, an FM Approved MJ adapter shall be used. Plain end pipe with or without an ID stiffener shall not be installed into the hub of a mechanical joint component. Unlisted Mechanical couplings and external joint restraints shall not be used to connect FM Approved polyethylene pipe nor fittings.

3.4 Flange Installation

  • Mechanical joint and flange connections shall be installed in accordance with the manufacturer’s recommended procedure. MJ adapters and flanges shall be centered and aligned to the mating components before assembling and tightening bolts. In no case shall MJ gland or flange bolts be used to draw the connection into alignment. Bolt threads shall be lubricated and flat washers should be used under the nuts. Bolts shall be evenly tightened according to the tightening pattern and torque step recommendations of the manufacturer. At least 1 hour after initial assembly, flange connections shall be re-tightened following the tightening pattern and torque step recommendations of PPI TN-38. The final seating torque shall be as recommended by the specifying engineer IAW Tn-38 guidance.

4. Installation

4.1 General

  • When delivered, a receiving inspection shall be performed and any shipping damage shall be reported to the manufacturer within 7 days. Installation shall be in accordance with ASTM D 2774, manufacturer’s recommendations, the PPI Polyethylene Pipe Handbook, and this specification. All precautions shall be taken to ensure a safe working environment in accordance with all applicable safety codes and standards.

4.2 Excavation

  • Trench and trenchless installations shall conform to the plans and drawings, as otherwise authorized in writing by the project engineer or his approved representative, and in accordance with all applicable codes. Where necessary, trench walls shall be shored or reinforced and all precautions shall be taken to ensure a safe working environment.

4.3 Large Diameter Fabricated Fittings

  • A maximum of one leg of a fabricated directional fitting of 16” IPS & DIPS or larger diameter shall be butt fused to the end of a pipe string. The remaining fitting connections shall be made in the trench using butt fusion, flange, MJ, or Electrofusion couplers. Flange and MJ adapter connections shall be assembled and tightened in accordance with the TN-38 and AWWA C600. Handling, lifting, moving or lowering a 16” IPS & DIPS or larger diameter fabricated fitting that is connected to more than one pipe length is prohibited. If multiple legs of large diameter fittings are fused to long pipe strings and then moved without proper support or 78 Industrial PE Technical Handbook 2016 design consideration, damage to the fitting may occur. The contractor, at his expense, shall correct fitting damage caused by such improper handling.

4.4 Foundation & Bedding

  • Pipe shall be laid on grade and on a stable foundation. Unstable trench bottom soils shall be removed and a 6” foundation or bedding of compacted Cass I material shall be installed to pipe bottom grade. Excess groundwater shall be removed from the trench before laying the foundation or bedding for the pipe. A trench cut in rock or stony soil shall be excavated to 6” below pipe bottom grade and brought back to grade with compacted Class I bedding. All ledge rock, boulders and large stones shall be removed. (ASTM D2774 & D2321)

4.5 Pipe Handling

  • When lifting with slings, only wide fabric choker slings capable of safely carrying the load shall be used to lift, move or lower pipe and fittings. Lifting or moving polyethylene pipe or components using wire rope and chain is prohibited.

4.6 Backfilling

  • Embedment material soil type and particle size shall be in accordance with ASTM D 2774. Embedment shall be placed and compacted to at least 90% Standard Proctor Density in 6” lifts to at least 6” above the pipe crown. During embedment placement and compaction, care shall be taken to ensure that the haunch areas below the pipe spring-line are completely filled and free of voids. Properly formulated and poured quick setting flowable-fill is allowed.

4.7 Protection against shear and bending loads

  • In accordance with ASTM D 2774, connections shall be protected where an underground polyethylene branch or service pipe is joined to a branch fitting such as a service saddle, branch saddle or tapping tee on a main pipe and where pipes enter or exit casings or walls. The area surrounding the connection shall be embedded in properly placed, compacted backfill, preferably in combination with a protective sleeve or other mechanical structural support to protect the polyethylene pipe against shear and bending loads. Properly formulated and poured quick setting flowable-fill is allowed.

4.8 Final Backfilling

  • Final backfill shall be placed and compacted to finished grade. Native soils may be used provided they are free from debris, stones, boulders, clumps, frozen clods or the like larger than 8” in their largest dimension.

5. Testing

5.1 Fusion Quality

  • The contractor shall ensure the field set-up and operation of the fusion equipment and the fusion procedure used by the contractor’s fusion operator while on site. Upon request by the owner, the contractor shall verify field fusion quality by making and testing a trial fusion. The trial fusion shall be allowed to cool completely, then test straps shall be cut out and bent strap tested in accordance with ASTM F2620. If the bent strap test of the trial fusion fails at the joint, the field fusions represented by the trial fusion shall be rejected. The contractor at his expense shall make all necessary corrections to equipment, set-up, operation and fusion procedure, and shall re-make the rejected fusions.

5.2 Acceptance Leak Testing

  • Hydrostatic leak testing shall be conducted in accordance with the guidance of the Plastic Pipe Institute Technical Note #46: http://www.plasticpipe.org/pdf/tn-46-guidance-field-hydro-test-hdpe-pressure-considerations.pdf and ASTM F2164. Pneumatic pressure testing is prohibited.t



Benefits & features


FM – Factory Mutual Global

… is the world’s largest industrial property insurance and risk management organization.

FM – Approval

….provides certification that Georg Fischer Central Plastics product design and manufacturing, meets your fire system protection needs.

FM – Critical elements

… Fire protection systems require moving water through pipes from its source to its final point of use. Underground pipe and fittings are considered the most critical components.

FM – Performance

… fire prevention systems must be extremely reliable and capable of safely withstanding both internal and external stresses over long periods of time. Rigorous testing and auditing by FM

Comparison of HDPE FM solutions for underground fire protection systems


Design-Flow RED

FM Approved

Longevity (Up to 100 year design life)     X
Resistant to Surge X   X
Resistant to Crack Propagation X   X
Corrosive Resistance   X X
Reduced Insurance Premiums     X
Non-Gasket Joining     X

Earthquake Resistant


Freeze Tolerant     X
Ductile Material X   X
Scratch Tolerant X   X