Installing, maintaining, and troubleshooting plumbing systems requires specific knowledge of industry standardized measurements, construction codes, and specialized components of plumbing systems. While locally adopted plumbing codes apply to these systems and components, manufacturer installation and use instructions should be followed. Many common plumbing parts and materials like pipes and fittings do not come with instructions and should be sized and installed to comply with locally adopted plumbing and building codes.
A pipe or fitting’s ability to hold pressure, survive hot or cold temperatures, and endure natural elements is limited by it’s chemical composition, wall strength, and integrity of the sealing method used to join individual components. Schedule is the term used in referring to “plastic” (PVC, ABS, CPVC) pipe’s wall thickness, with lower numbers representing thinner walled pipes. The most common sizes used in residential construction are Schedule 40 (thinner wall used in drain, waste and vent applications) and Schedule 80 (thicker wall used in pressurized water applications). Several material types are approved for use in piping system that serve different purposes in a complete plumbing system to include water supply, and waste, drain and vent (DWV). The following table indicates the type of plumbing system that various types of piping are generally allowed in residential and light commercial construction:
Common Material Types Supply Waste Drain Vent Copper Yes No No No PEX Yes No No No PVC Yes* Yes Yes Yes CPVC Yes** No No No ABS No Yes Yes Yes Cast Iron No Yes Yes Yes No-hub No Yes Yes Yes Galvanized Pipe Yes No No No Black Iron Pipe*** No No No NoFitting are used to join and redirect pipes and components to form complete plumbing systems. Due to the variety of designs of plumbing system components, fittings also facilitate adaptations from one size diameter of pipe or fitting to another. While many styles of fittings are used in most all types of systems, plumbing codes only allow some fittings to be used in particular type of plumbing system (supply or DWV) and have strict requirements as to how they are to be incorporated into the system (ex: compression fittings and unions should never be used inside of walls).
Fittings by Clifford Rutherford, Rosemary Rutherford & Gwen Arkin is licensed under CC BY 4.0
Fitting Supply Waste Drain Vent Coupler Yes Yes Yes Yes 90 degree elbow or offset Yes No Yes Yes 90 degree sweep No Yes Yes Yes 45 degree elbow or offset Yes No Yes Yes 45 degree sweep No Yes Yes Yes Tee Yes No No Yes Tee-Wye No Yes Yes Yes Sanitary Tee No Yes Yes Yes Adapter Yes Yes Yes Yes Bushing Yes Yes Yes Yes No-hub No Yes Yes Yes
Nominal Pipe Size Outside Diameter Wall Thick. (Sch 40) Wt. Per Ft. (Sch 40) Wall Thick. (Sch 80) Wt. Per Ft. (Sch 80) 1/8 0.405 0.068 0.245 0.095 0.315 1/4 0.540 0.088 0.425 0.119 0.535 3/8 0.675 0.091 0.568 0.126 0.739 1/2 0.840 0.109 0.851 0.147 1.088 3/4 1.050 0.113 1.131 0.154 1.474 1 1.315 0.133 1.679 0.179 2.172 1-1/4 1.660 0.140 2.273 0.191 2.997 1-1/2 1.900 0.145 2.718 0.200 3.631 2 2.375 0.154 3.653 0.218 5.022 2-1/2 2.875 0.203 5.793 0.275 7.661 3 3.500 0.216 7.576 0.300 10.250 3-1/2 4.000 0.226 9.109 0.318 12.510 4 4.500 0.237 10.790 0.337 14.980 5 5.563 0.258 14.620 0.375 20.780 6 6.625 0.280 18.970 0.432 28.570 8 8.625 0.322 28.550 0.500 43.390 10 10.750 0.365 40.480 0.500 54.740 12 12.750 0.375 49.560 0.500 65.420
Pipe Glues & Primers by Gwen Arkin is licensed under CC BY 4.0
The use of cleaners, primers, and glues is specific to slip fitting applications and the chemical composition of the “plastic” piping being used. Chemical resistant gloves should be worn when using these chemical process adhesives as prolonged skin contact can result in irritation or chemical burn. Latex and vinyl gloves are not chemically resistant when used with some solvents, primers, and glues.
Always consult manufacture directions for set times of cements and glues before pressurizing any glued plumbing assembly. When assembling fittings and pipes, cleaners, primers and glues should be swabbed over the entire joint surface of both the male and female slip fitting. Although manufacturer directions may vary, in most cases a cleaner should be used, followed by a primer and then the solvent cement. Additionally, after application of the primer, the solvent cement should be applied immediately before the primer dries. Before the glue begins to set up, the male pipe or fitting is inserted fully into the female socket with a slight twisting motion. It is important to hold the joint firmly together until an initial setting of the glue is achieved, as glued fittings have a tendency to push apart as the chemical heats and expands.
Most manufacturers of these chemically reactive products have adopted colors in their products that identify the composition of material it is to be used with.
Primers and Cleaners (Clear or Purple) Formulated to remove contaminates and chemically etch plastic piping. While some cleaners are clear, purple tinted primer stains white PVC enabling the user to ensure that all surfaces requiring glue are properly cleaned and etched. All Purpose Cement (Clear) Used with PVC, ABS, and CPVC, but should never be used to join two of the different types together. Wet-or Dry (Rain-or-Shine™) Cement (Blue) For PVC in damp applications. However, care should be used to keep fittings as dry as possible as these types of glues do not always set well if assembly is submerged. Transition Cement (Green) Used to join ABS to PVC. Although not a common practice, some special circumstance and repair applications may require these two materials to be joined. CPVC Cement (Orange) Specially formulated to only be used with CPVC products. CPVC piping and fittings should only be joined to other types of products with threaded fittings. ABS Cement (Black) For ABS piping systems only. Note that primers should NOT be used for ABS pipe and that cleaner should be used in its place.Color Blocks by Jonathan Kevan is licensed under CC BY 4.0
Most pipe threads by themselves are not sufficient to create a complete seal in pressurized piping systems.
Teflon Tapes by Gwen Arkin is licensed under CC BY 4.0
IPS and NPT pipe threads require Polytetrafluoroethylene (PTFE) tape (Teflon™ by Chemours) to be applied to the male threads of fittings in order to obtain a complete seal. PTFE tape is available in widths of 1/2″, 3/4″ and 1″ and different weights or thicknesses (white-standard duty, pink-high density). The standard duty tape should be wrapped completely and evenly across the male threads approximately three to four times in the direction the threads turn to tighten the fitting. The easiest way to accomplish this is to place the tape roll in the left hand with the tape feeding toward the right from the bottom. While holding the male fitting with the right hand, place the end of the tape across the top of the fitting and turn the fitting clockwise. After securing the first 1 to 1-1/2 wraps, gently stretch the tape, continuing to turn while overlapping layers up and down the threads until 3 to four complete wraps are achieved evenly across the length of the male threads. Pull the tape firmly to break and thread male fitting into female fitting, securing with an appropriate wrench.
Standard or high density PTFE thread pipe cannot, by codes, be used for natural gas and propane applications. A chemically resistant yellow version is used for these flammable gas systems.
Pipe Dope by Gwen Arkin is licensed under CC BY 4.0
As with thread tape, pipe dope comes in PTFE and other compositions designed for water lines and for gas lines. While some people use pipe dope on top of thread tape but many manufactures claim that the is minimal or no benefit to using both products simultaneously. Some pipe dopes cannot be used on plastic piping, be sure to check manufacturer directions prior to use. Pipe dope is applied with a brush to the male threads of a piping joint and then the pipe is tightened into the female fitting and secured with an appropriate wrench.
Due to the ever rising cost of copper material, soldering of copper pipes and fittings in residential construction is rapidly becoming obsolete as PEX flexible water supply tubing and similar solderless products, that use crimping system technologies, are being recognized and approved for installation by industry codes. However, plumbers and building maintenance technicians should always be prepared to use soldering techniques to install and repair copper supply lines of all sizes in commercial and older residential systems.
To an uneducated homeowner, pipe fittings are as numerous and confusing as choosing the right screw or nail for a construction project. The materials vary and the specific purpose, although precise, seems daunting to figure out. Our plumbers in Houston & Rosenberg can help repair or repipe your yard. We can help repair and repipe gas lines and water lines, whatever you need, our plumbers can help! Here is a brief overview of pipe fittings, their purpose, and the materials offered.
Obviously, pipe fittings are attached to the end of pipes that allow them to change direction, control the flow, and change the diameter of the pipe. Being a non-trivial part of plumbing and piping systems, consulting us with your need is definitely advised to save yourself time, money, materials, and headaches.
Types of pipe fittings and their purposes:
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