Rogin Says Milder HVAC/Plumbing Conditions Soften Design Requirements



Industry Expert Marty Rogin, PE, says that the milder fluids and environments of HVAC, Plumbing and Fire Suppression Systems pipe allow for simpler design analysis and installation documentation. The favorable conditions allow building designers to outsource the detailed design of HVAC, Plumbing and FSS pipe as a “Delegated Design” resulting in schedules of guides, supports and expansion joints. “We generally only consider pipe expansion, with seismic loads where required,” said Rogin. SPED Update interviewed Mr. Rogin at his office at Metraflex in Chicago, IL.



Most Architects and Owners employed a General Contractor to perform the detailed engineering and construction for their building designs. According to Bob Burchette, Partner at Johnston Allison & Hord in Charlotte, NC, “Design delegation” is the shifting of various design responsibilities to the GC, outside of a formal Design-Build Contract, by way of the contract, specifications, or directives of the Owner. The General Contractor then delegates parts of the design to members of the bidding team or outside consultants and suppliers with specialized expertise. Firms with delegated design responsibility frequently “seal” the designs as Professional Engineers. 


Wording of the specification of piping work to be done is given in standardized clauses such as the following:



Most support components follow the familiar standards:


SP-69-2003. Pipe Hangers and Supports – Selection and Application 

SP-89-2003. Pipe Hangers and Supports - Fabrication and Installation Practices


Piping Engineering is governed by


B31.9 - 2017 Building Services Piping


Which has rules for the piping in industrial, institutional, commercial, and public buildings, and multi-unit residences, which does not require the range of sizes, pressures, and temperatures covered in B31.1. The Code prescribes requirements for the design, materials, fabrication, installation, inspection, examination, and testing of piping systems for building services. It includes piping systems in the building or within the property limits.


Delegated Design for HVAC or Plumbing piping will typically receive what is termed “Bid” and “Coordination” drawings.  “Bid” drawings which are scaled piping layouts suitable for the General Contractor to prepare a cost and schedule proposal. “Coordination” drawings are prepared by the GC and guide the routing and installation of piping in the field.  The field work is supported by support and expansion joint schedules prepared piping delegated design.

The delegated designer will typically supply:


  • Stress analysis
  • Design Calculations
  • Anchor Details
  • Guide details
  • Material Certificates
  • Welding Certificates

as required by the GC in their specifications. The delegated designer will seal the design as a professional engineering licensed in the state where the building is located.


For more information on Metraflex’s Delegated Design Services, consult: