Pharmaceutical drainage systems are critical infrastructure components that demand careful planning and execution. Beyond simply removing wastewater, these systems must safeguard product integrity, maintain a sterile environment, and comply with stringent regulatory requirements. A crucial aspect of drainage system design is the selection of appropriate materials. This article provides a comprehensive overview of the factors influencing material selection and the various materials commonly used in pharmaceutical drainage systems.

1. Materials of Construction for Drainage Systems: A Multifaceted Decision

Specifying a drainage system involves a complex decision-making process, where material selection plays a pivotal role. Numerous factors must be considered to ensure the system’s effectiveness, longevity, and safety. These factors include:

• Compliance with Local Legislative Requirements: Drainage systems must adhere to all applicable local building codes, environmental regulations, and industry-specific standards. These regulations often dictate permissible materials, design parameters, and discharge limits.
• Cost: The initial cost of materials and installation is a significant consideration. However, a balanced approach should consider long-term costs, including maintenance, repairs, and potential replacements.
• Availability of Material: The chosen materials should be readily available to ensure timely project completion and avoid delays.
• Ease of Jointing and Access Requirements: The ease of joining pipes and fittings is crucial for efficient installation and minimizing the risk of leaks. Access for future maintenance and repairs should also be considered during the design phase.
• Temperature Range of the Effluent: The drainage system must be able to withstand the temperature range of the effluent being discharged. Extreme temperatures can damage certain materials, leading to leaks or system failure.
• Nature of the Effluent: The chemical composition of the effluent is a critical factor. Corrosive or toxic substances require specialized materials that are resistant to chemical degradation. pH levels, presence of organic solvents, and other chemical properties must be evaluated.
• Design Life of the System: The expected lifespan of the drainage system influences material selection. Materials should be chosen for their durability and resistance to degradation over time.
• Likelihood of Blockage: The potential for blockages should be assessed. Materials with smooth internal surfaces can minimize the buildup of debris and reduce the risk of blockages.
• Ease of Access for Maintenance: The design should allow for easy access to the drainage system for cleaning, inspection, and repairs. Strategically placed access points can simplify maintenance procedures.
• Strength and Durability: The materials must possess sufficient strength and durability to withstand external forces, such as soil pressure, traffic loads, and potential impacts.
• Fire Resistance: In certain applications, fire resistance may be a crucial consideration. Materials should be chosen based on their fire rating and ability to limit the spread of flames.
• Ease of Modification: The ability to easily modify the drainage system in the future can be advantageous. Materials that are easy to cut, join, and adapt can simplify future renovations or expansions.
• Minimization of Leakage Extent: The design should incorporate features that minimize the extent of damage caused by potential leaks. This may involve using leak detection systems, secondary containment, or other protective measures.
• Acceptability of Leakage: The consequences of a leak should be evaluated. In critical areas, such as sterile manufacturing facilities, even minor leaks can be unacceptable.

Specialized Drainage Applications

Beyond standard drainage considerations, certain applications require specialized solutions:

• Grease Traps: Kitchen drainage systems require grease traps to prevent fats, oils, and grease (FOG) from entering the sewer system. FOG can solidify and cause blockages, leading to costly repairs and environmental problems.
• Oil Separators: Car parks and other areas where oil spills are possible require oil separators to prevent oil from contaminating the wastewater.
• Bunds: Oil tanks and chemical stores should be surrounded by bunds to contain any spills or leaks. Bunds prevent hazardous materials from spreading and contaminating the environment.
• Double Wall Tanks: Double-walled tanks provide an extra layer of protection for storing hazardous liquids. The outer wall acts as a secondary containment in case of a leak from the inner wall.
• Laboratory Drainage: Laboratory drainage systems often handle small volumes of aggressive chemicals. “Catchpots” can be used to facilitate local dilution of waste and provide maintenance access for cleaning. Separate drainage systems may be necessary if different effluent types are likely to react or gel when mixed.

Materials Used in Pharmaceutical Drainage Systems

Pharmaceutical drainage systems utilize a variety of materials, each with its own advantages and disadvantages:

Metal Materials:

• Cast Iron: Cast iron is a traditional material known for its strength and durability. However, it can be heavy and susceptible to corrosion.
• Galvanized Steel: Galvanized steel is a common choice, offering a balance of strength and corrosion resistance. Modern galvanized steel systems often incorporate jointing systems that allow for movement during the system’s lifespan.
• Stainless Steel: Stainless steel is highly corrosion-resistant and ideal for demanding applications. It can be used as pipe or tube, joined on-site by welding, or as push-fit pipe systems for easier installation.
• Copper: Copper is readily available and easy to join using various techniques. However, it can be susceptible to corrosion with certain water types.

Plastics:

A wide range of plastic materials is available, each with specific properties:

• uPVC (Unplasticized Polyvinyl Chloride): uPVC is a cost-effective and versatile plastic commonly used for drainage systems. It is resistant to many chemicals but may not be suitable for high-temperature applications.
• ABS (Acrylonitrile Butadiene Styrene): ABS is a tough and impact-resistant plastic often used for drain, waste, and vent (DWV) systems.
• HDPE (High-Density Polyethylene): HDPE is a flexible and durable plastic known for its chemical resistance and ability to withstand low temperatures.
• PP (Polypropylene): PP is similar to HDPE but offers higher temperature resistance. It is often used for chemical drainage.
• PTFE (Polytetrafluoroethylene): PTFE, also known as Teflon, is highly chemical resistant and used for specialized applications involving aggressive chemicals.
• PVDF (Polyvinylidene Fluoride): PVDF offers excellent chemical resistance and is often used in demanding applications, such as pharmaceutical and chemical processing.
• Specialist Materials (e.g., Vulcathene): Specialized plastic materials are available for specific applications, such as handling highly corrosive or toxic substances.

Plastic systems can be joined mechanically or, depending on the material, by heat or solvent welding. When using solvent welding, the effluent type must be considered when selecting the appropriate solvent.

Other Materials:

• Borosilicate Glass: Borosilicate glass is highly chemical resistant and often used in laboratory drainage systems. It is typically joined using elastomer seals and clamp rings.
• Lined Systems: Metal pipes can be lined with various materials, such as plastics, glass, or rubber, to enhance their chemical resistance and provide greater mechanical strength and temperature tolerance.
• Clay: Clay pipes are traditionally used for underground drainage systems. However, they may not be suitable for hot wastewater discharges, such as WFI blowdown, which can degrade the pipework over time.
• Reinforced Concrete: Reinforced concrete pipes are used for underground systems where high strength and durability are required.

2. Traps: Preventing Backflow and Odors

Traps are essential components of drainage systems that prevent backflow of foul odors and gases from the sewer system into the building. They also trap solids and debris, preventing them from entering the drainage pipes and causing blockages. Two basic trap designs are commonly used:

• Bottle or Tubular Trap: Bottle or tubular traps are suitable for waste that is free-flowing and does not contain particulate matter. Any particulate matter denser than the effluent will settle in the base of the trap.
• “P” Trap: “P” traps are designed to handle waste that is likely to contain solids. The design of the “P” trap ensures that the solids are flushed away with the effluent flow. Variations of the “P” trap include those with a vertical inlet, a horizontal outlet, an angled outlet (“S” trap), or a horizontal inlet and outlet (“running” trap).

A Critical Element of Pharmaceutical Facility Design

The selection of materials for pharmaceutical drainage systems is a critical decision that impacts the system’s performance, longevity, and safety. A thorough understanding of the factors discussed in this article, coupled with careful consideration of the specific requirements of each application, is essential for designing and installing effective and compliant drainage systems. By prioritizing material compatibility, proper installation techniques, and ongoing maintenance, pharmaceutical manufacturers can minimize the risks associated with drainage systems and ensure the continued integrity of their manufacturing operations.