Piping

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Large-scale piping system in an HVAC mechanical room Mechanical room.jpg
Large-scale piping system in an HVAC mechanical room

Within industry, piping is a system of pipes used to convey fluids (liquids and gases) from one location to another. The engineering discipline of piping design studies the efficient transport of fluid. [1] [2]

Contents

Industrial process piping (and accompanying in-line components) can be manufactured from wood, fiberglass, glass, steel, aluminum, plastic, copper, and concrete. The in-line components, known as fittings, [3] valves, and other devices, typically sense and control the pressure, flow rate and temperature of the transmitted fluid, and usually are included in the field of piping design (or piping engineering), though the sensors and automatic controlling devices may alternatively be treated as part of instrumentation and control design. Piping systems are documented in piping and instrumentation diagrams (P&IDs). If necessary, pipes can be cleaned by the tube cleaning process.

Piping sometimes refers to piping design, the detailed specification of the physical piping layout within a process plant or commercial building. In earlier days, this was sometimes called drafting, technical drawing, engineering drawing, and design, but is today commonly performed by designers that have learned to use automated computer-aided drawing or computer-aided design (CAD) software.

Plumbing is a piping system with which most people are familiar, as it constitutes the form of fluid transportation that is used to provide potable water and fuels to their homes and businesses. Plumbing pipes also remove waste in the form of sewage, and allow venting of sewage gases to the outdoors. Fire sprinkler systems also use piping, and may transport nonpotable or potable water, or other fire-suppression fluids.

Piping also has many other industrial applications, which are crucial for moving raw and semi-processed fluids for refining into more useful products. Some of the more exotic materials used in pipe construction are Inconel, titanium, chrome-moly and various other steel alloys.

Engineering sub-fields

Generally, industrial piping engineering has three major sub-fields:

Stress analysis

Process piping and power piping are typically checked by pipe stress engineers to verify that the routing, nozzle loads, hangers, and supports are properly placed and selected such that allowable pipe stress is not exceeded under different loads such as sustained loads, operating loads, pressure testing loads, etc., as stipulated by the ASME B31, EN 13480, GOST 32388, RD 10-249 or any other applicable codes and standards. It is necessary to evaluate the mechanical behavior of the piping under regular loads (internal pressure and thermal stresses) as well under occasional and intermittent loading cases such as earthquake, high wind or special vibration, and water hammer. [4] [5] This evaluation is usually performed with the assistance of a specialized (finite element) pipe stress analysis computer programs such as AutoPIPE, [6] CAEPIPE, [7] CAESAR, [8] PASS/START-PROF, [9] or ROHR2. [10]

In cryogenic pipe supports, most steel become more brittle as the temperature decreases from normal operating conditions, so it is necessary to know the temperature distribution for cryogenic conditions. Steel structures will have areas of high stress that may be caused by sharp corners in the design, or inclusions in the material. [11]

Materials

The material with which a pipe is manufactured often forms as the basis for choosing any pipe. Materials that are used for manufacturing pipes include:

History

Ukraine, Olbia, elements of water pipes, the beginning of our era. Mykolayiv Regional Museum of Local History Ol'viia vodoprovidni trubi 2000 rokiv tomu.jpg
Ukraine, Olbia, elements of water pipes, the beginning of our era. Mykolayiv Regional Museum of Local History

Early wooden pipes were constructed out of logs that had a large hole bored lengthwise through the center. [13] Later wooden pipes were constructed with staves and hoops similar to wooden barrel construction. Stave pipes have the advantage that they are easily transported as a compact pile of parts on a wagon and then assembled as a hollow structure at the job site. Wooden pipes were especially popular in mountain regions where transport of heavy iron or concrete pipes would have been difficult.

Wooden pipes were easier to maintain than metal, because the wood did not expand or contract with temperature changes as much as metal and so consequently expansion joints and bends were not required. The thickness of wood afforded some insulating properties to the pipes which helped prevent freezing as compared to metal pipes. Wood used for water pipes also does not rot very easily. Electrolysis does not affect wood pipes at all, since wood is a much better electrical insulator.

In the Western United States where redwood was used for pipe construction, it was found that redwood had "peculiar properties" that protected it from weathering, acids, insects, and fungus growths. Redwood pipes stayed smooth and clean indefinitely while iron pipe by comparison would rapidly begin to scale and corrode and could eventually plug itself up with the corrosion. [14]

Standards

Stacking of a connected pipeline for transportation of oil products Stacking of a connected pipeline for transportation of oil products.jpg
Stacking of a connected pipeline for transportation of oil products

There are certain standard codes that need to be followed while designing or manufacturing any piping system. Organizations that promulgate piping standards include:

See also

Related Research Articles

<span class="mw-page-title-main">Plumbing</span> Systems for conveying fluids

Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses pipes, valves, plumbing fixtures, tanks, and other apparatuses to convey fluids. Heating and cooling (HVAC), waste removal, and potable water delivery are among the most common uses for plumbing, but it is not limited to these applications. The word derives from the Latin for lead, plumbum, as the first effective pipes used in the Roman era were lead pipes.

A flange is a protruded ridge, lip or rim, either external or internal, that serves to increase strength ; for easy attachment/transfer of contact force with another object ; or for stabilizing and guiding the movements of a machine or its parts. Flanges are often attached using bolts in the pattern of a bolt circle.

<span class="mw-page-title-main">Cathodic protection</span> Corrosion prevention technique

Cathodic protection is a technique used to control the corrosion of a metal surface by making it the cathode of an electrochemical cell. A simple method of protection connects the metal to be protected to a more easily corroded "sacrificial metal" to act as the anode. The sacrificial metal then corrodes instead of the protected metal. For structures such as long pipelines, where passive galvanic cathodic protection is not adequate, an external DC electrical power source is used to provide sufficient current.

<span class="mw-page-title-main">Hydrostatic test</span> Non-destructive test of pressure vessels

A hydrostatic test is a way in which pressure vessels such as pipelines, plumbing, gas cylinders, boilers and fuel tanks can be tested for strength and leaks. The test involves filling the vessel or pipe system with a liquid, usually water, which may be dyed to aid in visual leak detection, and pressurization of the vessel to the specified test pressure. Pressure tightness can be tested by shutting off the supply valve and observing whether there is a pressure loss. The location of a leak can be visually identified more easily if the water contains a colorant. Strength is usually tested by measuring permanent deformation of the container.

<span class="mw-page-title-main">Gasket</span> Type of mechanical seal

A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression. It is a deformable material that is used to create a static seal and maintain that seal under various operating conditions in a mechanical assembly.

<span class="mw-page-title-main">Pressure vessel</span> Vessel for pressurised gases or liquids

A pressure vessel is a container designed to hold gases or liquids at a pressure substantially different from the ambient pressure.

<span class="mw-page-title-main">High-density polyethylene</span> Class of polyethylenes

High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer produced from the monomer ethylene. It is sometimes called "alkathene" or "polythene" when used for HDPE pipes. With a high strength-to-density ratio, HDPE is used in the production of plastic bottles, corrosion-resistant piping, geomembranes and plastic lumber. HDPE is commonly recycled, and has the number "2" as its resin identification code.

Cross-linked polyethylene, commonly abbreviated PEX, XPE or XLPE, is a form of polyethylene with cross-links. It is used predominantly in building services pipework systems, hydronic radiant heating and cooling systems, domestic water piping, insulation for high tension electrical cables, and baby play mats. It is also used for natural gas and offshore oil applications, chemical transportation, and transportation of sewage and slurries. PEX is an alternative to polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC) or copper tubing for use as residential water pipes.

<span class="mw-page-title-main">Pipe (fluid conveyance)</span> Tubular section or hollow cylinder

A pipe is a tubular section or hollow cylinder, usually but not necessarily of circular cross-section, used mainly to convey substances which can flow — liquids and gases (fluids), slurries, powders and masses of small solids. It can also be used for structural applications; hollow pipe is far stiffer per unit weight than solid members.

Nominal Pipe Size (NPS) is a North American set of standard sizes for pipes used for high or low pressures and temperatures. "Nominal" refers to pipe in non-specific terms and identifies the diameter of the hole with a non-dimensional number. Specific pipe is identified by pipe diameter and another non-dimensional number for wall thickness referred to as the Schedule. NPS is often incorrectly called National Pipe Size, due to confusion with the American standard for pipe threads, "national pipe straight", which also abbreviates as "NPS". The European and international designation equivalent to NPS is DN, in which sizes are measured in millimetres, see ISO 6708. The term NB is also frequently used interchangeably with DN.

<span class="mw-page-title-main">Expansion joint</span> Construction assembly for absorbing thermally-induced volume changes

A expansion joint, or movement joint, is an assembly designed to hold parts together while safely absorbing temperature-induced expansion and contraction of building materials. They are commonly found between sections of buildings, bridges, sidewalks, railway tracks, piping systems, ships, and other structures.

<span class="mw-page-title-main">Piping and plumbing fitting</span> Connecting pieces in pipe systems

A fitting or adapter is used in pipe systems to connect sections of pipe or tube, adapt to different sizes or shapes, and for other purposes such as regulating fluid flow. These fittings are used in plumbing to manipulate the conveyance of fluids such as water for potatory, irrigational, sanitary, and refrigerative purposes, gas, petroleum, liquid waste, or any other liquid or gaseous substances required in domestic or commercial environments, within a system of pipes or tubes, connected by various methods, as dictated by the material of which these are made, the material being conveyed, and the particular environmental context in which they will be used, such as soldering, mortaring, caulking, Plastic welding, welding, friction fittings, threaded fittings, and compression fittings.

<span class="mw-page-title-main">Thermowell</span> Metal housing which protects a temperature sensor immersed in a fluid

Thermowells are cylindrical fittings used to protect temperature sensors installed to monitor industrial processes. A thermowell consists of a tube closed at one end and mounted on the wall of the piping or vessel within which the fluid of interest flows. A temperature sensor, such as a thermometer, thermocouple, or resistance temperature detector, is inserted in the open end of the tube, which is usually in the open air outside the piping or vessel and any thermal insulation.

Black powder is an industry name for the abrasive, reactive particulate contamination present in all gas and hydrocarbon fluid transmission lines. Black powder ranges from light brown to black, and the mineral makeup varies per production field around the world.

<span class="mw-page-title-main">Plastic pipework</span> Tubular section or hollow cylinder made of plastic

Plastic pipe is a tubular section, or hollow cylinder, made of plastic. It is usually, but not necessarily, of circular cross-section, used mainly to convey substances which can flow—liquids and gases (fluids), slurries, powders and masses of small solids. It can also be used for structural applications; hollow pipes are far stiffer per unit weight than solid members.

ROHR2 is a CAE system for pipe stress analysis from SIGMA Ingenieurgesellschaft mbH, based in Unna, Germany. The software performs both static and dynamic analysis of complex piping and skeletal structures, and runs on Microsoft Windows platform.

FRP is a modern composite material of construction for chemical plant, pulp and paper mill, and food and pharmaceutical equipment like tanks and vessels. Chemical equipment that range in size from less than a metre to 20 metres are fabricated using FRP as material of construction.

A pipe support or pipe hanger is a designed element that transfer the load from a pipe to the supporting structures. The load includes the weight of the pipe proper, the content that the pipe carries, all the pipe fittings attached to pipe, and the pipe covering such as insulation. The four main functions of a pipe support are to anchor, guide, absorb shock, and support a specified load. Pipe supports used in high or low temperature applications may contain insulation materials. The overall design configuration of a pipe support assembly is dependent on the loading and operating conditions.

HDPE pipe is a type of flexible plastic pipe used to transfer fluids and gases. It is often employed for replacing aging concrete or steel main pipelines. Constructed from the thermoplastic HDPE, it has low permeability and robust molecular bonding, making it suitable for high-pressure pipelines. HDPE pipe is often used for water mains, gas mains, sewer mains, slurry transfer lines, rural irrigation, fire-suppression system supply lines, electrical and communication conduits, and stormwater and drainage pipes.

A variety of non-destructive examination (NDE) techniques are available for inspecting plastic welds. Many of these techniques are similar to the ones used for inspecting metal welds. Traditional techniques include visual testing, radiography, and various ultrasonic techniques. Advanced ultrasonic techniques such as time of flight diffraction (TOFD) and phased-array ultrasonics (PAUT) are being increasingly studied and used for inspecting plastic pipeline welds. Research in the use of optical coherence tomography (OCT) and microwave reflectrometry has also been conducted.

References

  1. Editors: Perry, R.H. and Green, D.W. (1984). Perry's Chemical Engineers' Handbook (6th ed.). McGraw-Hill Book Company. ISBN   0-07-049479-7.{{cite book}}: |author= has generic name (help)CS1 maint: multiple names: authors list (link)
  2. Editor: McKetta, John J. (1992). Piping Design Handbook. Marcel Dekker, Inc. ISBN   0-8247-8570-3.{{cite book}}: |author= has generic name (help)
  3. "Pipe fitting manufacturer". Yaang. Archived from the original on 27 February 2016. Retrieved 6 March 2016.
  4. Archived 29 May 2006 at the Wayback Machine
  5. Power Piping: ASME B31.1
  6. "Piping Design And Pipe Stress Analysis Software – AutoPIPE". bentley.com. Archived from the original on 9 November 2016. Retrieved 22 December 2017.
  7. "SST Systems, Inc. | CAEPIPE: Fast – Efficient Pipe Stress Analysis". Archived from the original on 29 January 2010. Retrieved 27 September 2010.
  8. "Intergraph CAESAR II – Pipe Stress Analysis". coade.com. Archived from the original on 2 May 2015. Retrieved 4 June 2015.
  9. "PASS/START-PROF – Pipe Stress Analysis". passuite.com. Archived from the original on 8 January 2019. Retrieved 1 March 2019.
  10. "SIGMA/ROHR2 – Pipe Stress Analysis Software". rohr2.com. Archived from the original on 12 April 2021. Retrieved 16 February 2022.
  11. Temperature & Stress Analysis Archived 22 February 2014 at the Wayback Machine Piping Technology and Products, (retrieved February 2012)
  12. "What is HDPE Pipe?". Acu-Tech Piping Systems. Retrieved 20 March 2019.
  13. "BBC – A History of the World – Object : wooden water pipe". BBC. Archived from the original on 7 May 2016. Retrieved 10 March 2016.
  14. "Piping water through miles of Redwood". Popular Science : 74. December 1918. Archived from the original on 28 December 2017.
  15. H. "ASTM A252 Pipe Pile". China Huayang Steel Pipe. Archived from the original on 16 October 2014.
  16. "API 5L Specification Line Pipe (1) – API Terms and Definitions". China Huayang Steel Pipe. Archived from the original on 16 October 2014.

Further reading