What is fitting in civil engineering?

08 Apr.,2024

 

4.1 Piping & Fittings

Pipes

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 No

Fittings

Fitting 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).

Fitting Terminology

National Pipe Thread (NPT)
American standard thread used in pluming and piping systems. It may also be referred to as MPT or MNPT for male external threads and FPT or FNPT for female internal threads. A thread sealant of some type should always be used to obtain a leak free seal (except for NPTF). Iron Pipe Size (IPS)
Older pipe sizing system still in use by some industries, including PVC pipe manufacturers. Slip fittings
Slip fittings require a male component with a particular outside diameter to be joined with a female component with a similarly sized inside diameter either by solvent, glue, or, when using copper components, soldering. Couplings
Couplings are designed to join two pipes of equal diameter. Couplings can be slip-to-slip or female thread to female thread. Bushings
This fitting allows a pipe or fitting to be reduced to a smaller size and are made to be inserted into a pipe, inside slip, or female thread. Bushings outside diameter can be male thread or male slip with the inside diameter, being of the same style (slip or thread) as the outside, dictating the size the piping system is reduced to. Adapters
Similar to bushings, adapters are used to convert pipes and fittings from one size to another. Unlike bushings, adapters can allow for conversion from slip to thread applications an, in some cases, one piping material type to another. Elbows
Elbows normally create a 90° or 45° change in direction of a piping system. 22-1/2° fittings are also available for some piping systems. Depending on the material, elbows come in female slip-to-female slip, female slip-to-female slip, slip-to-female thread, slip-to-male thread. PVC and Copper female slip-to-male slip elbows are referred to as street elbows and they are used for close turns and swivel to fit connections. Tees
Tees connect pipes at 90 degree angles divide the flow of a single line into two or more. Tees can also be used to reduce the size of a branch feeding off of a main line. Tees are normally fitted with female threads in each direction. Plugs
Plugs are male thread or male slip and designed to seal off unused plumbing system branches or unused component outlets. Caps
Caps, like plugs, are designed to seal off unused plumbing system branches or unused component outlets, but have female slip fittings or threads. Unions Unions facilitate the removal and repair of system components and consist of one fitting having a swivel nut which attaches to the other fitting which has a male threaded adapter with a flange or compression type seal. Compression fittings Compression fittings are sometimes used to install plumbing system components and make quick repairs on smooth outside diameter pipes like PVC and copper. Compression fittings require that a soft brass metal sleeve in copper applications, and Teflon or pliable washer in PVC applications, is compressed around the piping material by an adjustment nut to seal the fitting. Wyes
Wyes are Y-shaped fittings that allow one pipe to be joined to another at a 45 degree angle. Wyes are not used in water supply systems, but are common in DWV systems where hard turns slow the flow of waste. Tee-Wyes
Tee-Wyes are similar to standard wyes but provide an additional 45 degree branch. Sanitary Tees
Sanitary Tees should be used when connecting a horizontal run, such as a waste arm to a vent stack or vertical riser. They are only used to go from the horizontal to vertical plane. Clean-Outs
Clean-Outs are threaded plugged access points in a DWV system used for clearing clogged lines with augers and inspecting DWV systems with cameras. Plumbing system codes dictate how many clean-outs should be in a waste system by the length of run and the amount of turns in the system.

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

Solvent Cleaners, Primers, & Cements or Glues

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.

Color and Material

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

 

Difference Between PVC Cement Types & Primer

Differences Between CPVC, DWV PVC, Schedule 40 PVC, and Schedule 80 PVC

Threaded Pipe Fitting Assembly

Most pipe threads by themselves are not sufficient to create a complete seal in pressurized piping systems.

Thread Tape

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

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.

Copper Pipe Fitting and Soldering

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.

Simple Steps for Soldering

  1. Clean the pipe well.
  2. Clean the fitting well.
  3. Apply an even coat of flux.
  4. Don’t get the fitting too hot.

 

How to Solder Pipe

Plumbing Pipes, Fittings, and Their Uses

Types of Pipes and Fittings

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:

  • Elbows: Used to change the angle or direction of the pipe run. Most commonly in 90 degrees and 45 degree turns. The sweep of the fitting describes how fast a transition or change in direction is made.
  • Street Elbows: One end of the pipe fitting has male threads and the other end has female threads. These are common in galvanized steel and copper pipe. They are convenient because they do away with the need for a nipple and work well in tight quarters.
  • Tee Fittings: Shaped like the letter T. Allows for branch lines.
  • Couplings: Used to join two straight pieces of pipe of the same diameter.
  • Reducers: Used to join pipes of different diameters. Makes a gradual change in diameter.
  • Bushings: Used to make the diameter of a pipe fitting smaller. They are different from reducers because they make an abrupt change in diameter and take little space.
  • Unions: Used to join pieces of pipe where pipes cannot be turned or when a piece of equipment may have to be removed for maintenance or replacement.
  • Adaptor Fittings: Used to change the end of a non-threaded pipe to male or female threads as needed. Most commonly used in copper and plastic plumbing jobs.
  • Caps: Used to close the end of a dead-end pipe.
  • Plugs: Used to close an ending on a pipe fitting normally used for inspection or cleanout.
  • Nipples: Short lengths of pipe threaded at both ends.
  • Wyes: Used primarily to gain inside access to DWV (drain-waste-vent) systems.
  • Valves: Devices that control the flow of liquid or gas through or from a pipe. (Compression valves, ball valves, sleeve-cartridge valves, ceramic disc valves, etc)
  • PVC Fittings: Come in a wide variety of configurations and may be glued (S) or threaded (T)
  • Copper Tubing Fittings: Use compression fittings. Common fittings are couplings, ells, and tees.

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What is fitting in civil engineering?

Types of Pipe Fittings and Their Uses