Image: Godrej Group Traditionally, metallic (steel, galvanised iron, cast-iron and electric resistance welded) pipes, plastic pipes, and cement (concrete cement and asbestos cement) pipes have been used in India. “Today, for water supply systems, allied composites such as polybutylene, polypropylene random copolymer plastic (PPR pipes), chlorination poly vinyl chloride (CPVC), cross-linked polyethene (PEX, XPE or XLPE) and composites such as PE Al PE (polyethylene aluminium polypropylene) are in use,” observes Prakasan TP, CEO, MEP-IEPC Business, Sterling and Wilson. “PVC is an established material for drainage in external and concealed applications. PVC, HDPE, foam core and polyethylene are widely used for drainage.” What’s trending? For cold and hot water applications, multi-layered CPVC-aluminium-CPVC composite pipes have been introduced, which offer higher strength and good impact resistance, says BSA Narayan, Managing Director, Maple Engg-Design Services (India) and Director, Executive Board, World Plumbing Council. “Also, for cold and hot water uses, the market has launched cross-linked polyethylene (PEX-a) pipes, which are flexible, easy and fast and neat to join with the expansion ring joining technique. For water supply applications, we are using multi-layer CPVC composite piping systems and PEX-a piping systems.” “We’re seeing dynamic changes in architectural design, such as open ceilings and complex structures; these are sometimes difficult to accommodate using straight down plumbing shafts and, therefore, composite and acoustic pipes are trending for internal use,” says Jaydeo Gavali, Project Designer-MEP Lead, Godrej Group. “We’re introducing acoustic horizontal drain pipes to avoid noise from wastewater and drainage systems. We’re also introducing PEX and plastic pipes for their durability, efficiency and workability. Also, prefabricated plumbing systems have vast scope.” “We prefer CPVC and UPVC pipes and source them from local dealers to boost their business,” says Deepthi KR, Managing Partner, Radian Engineering. Trending drainage pipes New products for drainage and sewerage systems include special multi-layered, high-density, low noise PP pipes that should be preferred because of their low-noise properties and reliable performance along with traditional UPVE pipes and fittings, suggests Narayan. “We are adopting new systems like the single-stack system, where only one pipe is used for soil and wastewater with a special fitting at each floor level, he adds. “We have started using multi-layered, high-density, low-noise piping systems and inspection chambers and manholes.” For his part, Gavali says, “We’re using HDPE drainage pipes as plastic buried drain pipes for zero leakage, no pollution, long life, corrosion resistance and easy installation.” The execution of drainage and water distribution has always remained challenging owing to the broad and long list of fittings and consumables maintenance at sites. Prakasan recommends the use of drafting and estimation tools, both 2D and 3D drawings, to accurately estimate these fittings. Piping to avert fire spreads Safety standards prescribe the installation of appropriate fire stops across all vertical and horizontal transitions in residential/commercial buildings, especially high-rises, where pipes in plumbing shafts are exposed internally, observes Prakasan. Pipes must be selected according to the functionality and fire susceptibility of a space, suggests Gavali. “Fire-rated pipes and control valves are preferable, especially in vulnerable areas like shafts.” “Where the interior design includes suspended ceiling pipes, the material of the pipes plays a critical role in establishing burn resistance, flame spread resistance, smoke generation resistance and thermal conductivity of the space,” says Gavali. “Some thermoplastic materials like PPR are not designed to withstand fire but CPVC is engineered to limit flammability and smoke generation with a limiting oxygen index as low as 60. CPVC’s flash ignition temperature is 900°F (482°C), making it far less susceptible to ignition than other thermoplastic materials and more susceptible than metal piping. Firewalls are designed to stop the spread of smoke and flame but they cannot stop heat transfer through the piping material. Here, CPVC performs better than metal piping.” Metal piping systems have been traditionally used in fire sprinkler applications but these have disadvantages such as being cumbersome to install and corrosive. Instead, Narayan suggests using CPVC pipes or UL marking pipes that provide the additional assurance of quality and fire safety. What’s holding back MEP? Metals like copper, steel, aluminium and stainless steel, and alloys such as dezincified brass and gunmetal are being used keeping in mind hygiene, long life and secure jointing systems, according to Prakasan. “However, choosing between material cost, functionality and lifecycle has been an eternal debate for design engineers, project management consultants, cost consultants, owners and contractors.” The Indian plumbing industry mostly comprises small and mid-sized contractors who are highly cost-conscious and have an outcome-based mindset, observes Gavali. Hence, new technological innovations are mostly introduced on the consulting and manufacturer’s end. “We are still critical of accepting new types of piping systems, such as HDPE, PPR, PEX, composite and high UPVC, in the commercial and residential segments, which could deliver major benefits. For instance, PEX pipes are flexible, resist scale build-up, corrosion and chlorine, can withstand temperature extremes, and are easily cut and installed. Composite, aluminium plastic composite, PPR pipes deliver improved resistance to impulse under low temperature, UV rays, high temperature and high pressure. Orange UPVC can replace hume pipes used for stormwater and underground drainage systems.” Gavali believes slow adoption is a pity as end-users are open to innovation. “Design and system changes are desirable, such as effective operative three stack and metering in mid-rise buildings for more efficient use of water; the use of inlet tanker pipe and stand risers when main supply fails, which can be used as a backup; condensate tanks to store AC coil drain water; and hot water piping systems to help save electricity and water,” he shares. “Pipe systems should be fitted to minimise the acoustic resonance transmitted through the pipe clamps to the building’s structure.” “The biggest challenges we face are demand for rework, changes to the list of sanitaryware selected at the concept stage, supplier delays, demand for uncertified products and frequent changes in product choices,” says Deepthi. “If these issues don’t come up, the plumbing job happens faster and smoother.” Missing materials Testing water supply systems before commissioning at 1.5x the working pressure is an established practice to ensure system integrity, Prakasan points out. “Correspondingly, pipes laid in horizontal alignment should be tested at 1-1.5x the working pressure. Mostly, PVC end plugs sealed using solvent cement are used for the ends of drainpipes. These plugs are mostly non-reusable and create waste pipe pieces every time. Alternative mechanical or rubber inflatable plugs can reduce waste and improve reliability but these aren’t available. Consequently, vertical drainage stacks are currently not tested. For larger diameter stormwater and sewer mains, air testing is advisable.” Indian companies have developed new products like pan connectors, swept-type concealed valves, backflow preventers, air admittance valves and special fittings for single-stack systems, observes Narayan. However, new products are continuously being developed globally. He would like Indian manufacturers to keep track of these new developments. We couldn’t agree more. MEP response to COVID-19 COVID-19 spreads by contact and through air. Therefore, the design of a plumbing system needs special attention to ensure safe and effective disposal to prevent virus spread through wastewater, explains Prakasan. How have execution and design MEP engineers stepped up to this challenge? According to Prakasan, they have realigned the process of material selection, cost optimisation, value engineering, lifecycle cost of ownership, system selection and compliance to prevalent codes and standards. “Water-sealed traps are a defence mechanism built into plumbing drainage systems,” he continues. “Codes and standards specify a minimum 50 mm water seal at each trap. However, full seal traps are now available within a height of 150 mm versus the traditional 230 mm traps. Connecting all the traps to the vertical stack (rather than double-trapping) is a good practice to secure the plumbing system.” It's time to do away with ‘Nahani’ traps, a short-changed 25 mm trap seal typically used by building design teams to reduce the sink in the wet area to cut waterproofing and plumbing fixtures/appurtenances costs, cautions Prakasan. New anti-bacterial and touchless sanitaryware are becoming trendier owing to the pandemic, according to Gavali. “Organised plumbing was relatively less affected by the pandemic because the segment has seen a lot of consolidation in the PVC/CPVC pipe segments and affordable and mid-income housing has seen strong growth in demand on the back of relief measures announced in 2020,” says Deepthi KR, Managing Partner, Radian Engineering. “COVID-19 has restricted opportunities for plumbers, as some potential customers have delayed getting work done owing to concerns about bringing illness home. Some plumbers aren’t adequately aware of how to get back to work with new business hygiene norms. Training will help the industry bounce back.” Training in plumbing The Pratham Education Foundation offers training in plumbing in regular courses as well as to groups of company workers and employees (recognition of prior learning), shares Shivaji N Kadam, Program Head-Plumbing, Pratham Education Foundation. “We help trained hands get placed in the construction industry.” Other activities of the plumbing training programme include demos on methods of water conservation, free plumbing check camps for government schools, awareness campaigns and free hands-on plumbing training in the community for different age groups. Practices for the best outcomes Plumbing systems will deliver the best outcomes if the following best practices are followed, says Deepthi: The drawings of the plumbing designer are adhered to. Clarification and guidance are sought from the product catalogue. Licensed installers with an established track record are used. A job mock-up is made and accepted; this eliminates flaws in repetitive work at different places. Onsite changes to concealed work are noted. A strong onsite material inventory system is established to eliminate shortcomings and pilferages. - CHARU BAHRI