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MEP prefabrication drawings
30 November 2020
Shalini John

Understanding the Challenges of MEP (M&E) Prefabrication Drawings

Current hero in the construction industry, prefabrication is something everyone wants a piece of – literally. As prefabrication extends to modular construction services, the creation of different types of MEP modules and the components installed in them, it becomes imperative to bolster design practices with the development of accurate and precise fabrication shop drawings and other fabrication drawing services, which in turn requires a comprehensive grasp of the requirements and standards of modules and modular construction.

Let’s look at what we mean by modules and the kind of components which are installed in them.

There are three basic types of prefabricated MEP modules. They are horizontal ceiling modules, vertical riser modules and plant modules. The design of these different module types typically adhere to the following guidelines:

  • MEP module structural requirements, including their weight and dynamic loading to be provided to the qualified structural personnel
  • Module support system to be installed according to approved shop drawings endorsed by main project engineer
  • Module supports need standard strut components and hardware, with mechanical connections and bridging from the modules
  • Supporting frames should be flexible and become smaller if required
  • Module supporting system should be light for easy installation, reduced building loads and minimal material wastage
  • In case of welded connections, painting with cold galvanizing zinc is required to prevent corrosion
  • For continuous service runs, modules are linked in tandem
  • Overhead components require independent support

Now, what are the different kinds of components that each type of module generally contains?

Horizontal Ceiling Modules

Typically, most or all MEP services are included in the ceiling module, such as:

  • Sprinklers
  • Chilled water supply and return pipes
  • Condensate drain pipes
  • Drains
  • Plumbing
  • Town gas
  • Medical gas systems
  • Electrical and extra low voltage cabling systems with trunking, tray or cable ladders
  • Air-conditioning/mechanical ventilation ductwork
  • Light fixtures

For sprinkler and plumbing services, the design of ceiling modules must consider:

Fire Safety
  • If the module height is more than 800 mm, a second layer of sprinklers must be installed following consultation with the relevant authorities for fire safety compliance.
  • If the module has a fire-rated duct, the module frame and supports must be fire-rated.
  • If the module is used in smoke stop and firefighting lobbies, a fire-resistant board must be included, conforming to country codes.
Water Leaks
  • It is possible for sanitary waste pipes and potable water pipes to leak, and horizontal ceiling module design must take that into consideration.
  • In narrow corridors, electrical services are installed above plumbing and sanitary services.
  • Acrylic/zinc sheets can be installed between water pipe joints and electrical services.
  • For wider corridors, electrical services can be installed adjacent to mechanical, sanitary and plumbing services, with a non-conducting divider between them.

It is essential to take the above requirements into consideration when creating fabrication shop drawings.

Vertical Riser Modules

This type of module typically consists of vertical riser ducts and pipes. Some of their main features are as follows:

  • Vertical services in each riser module are installed horizontally at ground level and then branch out to multiple floors.
  • Riser modules can be installed before erecting riser shaft walls.
  • Riser modules can also be lowered into the riser shaft through top floor openings.
  • Riser module design should include lifting lugs and brackets.
Plant Modules

Some of the components that prefabricated MEP plant modules comprise of are:

  • Control panels
  • Instruments on skids with lifting eyes for piping connections
  • Valves
  • Cable termination for power supply
  • Interfaces for automation systems and fire alarm systems

Plant modules that are pre-assembled, pre-wired and contain control panels may also include:

  • Water pump sets and hydro-pneumatic tank for boosting and transfer
  • Fire hose reel pump set with hydro-pneumatic tank
  • Vacuum pump sets
  • Air compressors
  • Cooling towers
  • Chillers
  • Chilled water and condensing water pumps
  • Air-condensing units
  • Air handling units (AHUs)
  • Fan coil units (FCUs)

The inclusion of a range of components in each type of MEP module needs an installation strategy that is as near foolproof as possible. Installation of different types of components can be tricky and needs a good understanding of the many elements involved, and they must be clearly represented in fabrication shop drawings.

Mechanical and piping installation work includes the use of:

  • Construction documentation
  • Pre-manufacturing and installation of pipework spools with supports
  • Installation of pumps, compressors, heat exchangers, pressure vessels and valves
  • Installation of cryopumps, cold boxes, gas valves boxes, pipelines for cryo fluid, vacuum lines,
  • Installation of fuel lines, transmission lines, wave guides, vacuum lines
  • Internal cleaning, touch-up paint, thermal insulation, cladding, labelling and tagging

Part of the installation strategy involves the workflow and processes that include following national standards. For superconducting joints, optical alignments, the mechanical and piping contractor must work with the companies executing the specific operations. The main contractor will have an ISO 9001 accredited quality system in accordance with country standards and construction and design rules, and the contractor must provide the necessary documentation for every stage of the work.

This installation strategy for prefabricated equipment can progress seamlessly with high-quality fabrication shop drawings. As creating these drawings are of critical importance, the challenges lie in finding the right partner to develop high-quality, accurate and clash-free drawings. An increasingly preferred option is an offshore partner with the required expertise, experience and design workflow to provide fabrication drawing services and modular construction services in a timely and cost-effective manner.

XS CAD has valuable experience providing DfMA modelling and fabrication drawing services for MEP engineers/designers, manufacturers and for design and build firms. Our range of services for structural, architectural and building engineering firms, such as consultants and contractors across the world, include modular construction models, prefabricated construction drawings and fabrication shop drawing services for prefabricated bathroom modules, a packaged plant room and other units. We create these models and drawings by using Revit, AutoCAD, Inventor and BIM 360 Design for cloud collaboration.