Piping

Isometric Piping Drawings

Also known as Isos, provide an easy visualization of complex piping in a plant as a 3 dimensional representation. Can be broken down further into a contractors' spool. Used by fabricating shops, purchasing groups and a contractor.

Lateral

An outlet 45 degrees to the run. Straight and reducing are available. The reduction is on the outlet not the run.

Isometric Piping Drawing Procedures

Guidelines for creating isometric piping drawings. -not drawn to scale -valves and small details may be drawn larger for added clarity -preferred north direction is up and to the right -contains the dimensions and bill of materials -usually shown as single line, except for fittings and nozzles -elbows are drawn square or rounded -welds are represented as heavy black dots or an X

Short Radius Return Bend

Has a center to center distance equal to 2x the nominal pipe size.

Long Radius Return Bend

Has a center to center distance equal to 3x the nominal pipe size.

90 degree Short Radius Elbow

Has a turn radius 1x the nominal pipe size.

Spools

Isometric drawings used to show the piping fabrication. Include the fittings, flanges and pipe.

Reducers

Used when a reduction in the run is required.

Piping Materials Cast Iron Pipe

Used where pressure and temperature is not critical as in water and drainage. Has a higher corrosion-resistance value.

Reducing Tee

A connection used to branch a pipeline off a run at 90 degrees when the outlet is of a smaller size.

Straight Tee

A connection used to branch a pipeline off a run at 90 degrees.

Pipe

A hollow body used for the connection between two or more pieces of equipment, tanks, valves, or whatever needs to be joined together for transporting liquids or gases. Standard and Sch. 40 have the same wall thicknesses up to 10". Extra Strong and Sch. 80 have the same wall thicknesses up to 8".

Welded Outlets

A right angled connection made by welding. 4 types: Weldolet, Threadolet, Sockolet and an Elbowlet.

90 degree Long Radius Elbow with a Long Tangent

An elbow with a long tangent on one end. Has a turn radius of 1.5 the nominal pipe size.

90 degree Long Radius Elbow

Has a turn radius of 1.5x the nominal pipe size.

Isometric Piping Dimensioning

Isometric drawing must contain information to allow welders or pipefitters to fabricate the pipe or allow draftsmen to prepare a spool or a shop fabrication drawing. -shown as either centerline of pipe to centerline of pipe or centerline of pipe to flange face -weld locations are not dimensioned -extension lines are drawn parallel to the isometric axis -dimension lines are drawn parallel to the dimensioned pipe -piping is dimensioned to the nearest 1 mm or 1/16" -gasket thicknesses are included in the valve dimension for any valve within the iso -the flow direction is often shown -special details or notes may be required such as field fabrication and service connections

45 degree Elbow

Long radius only. 1.5 NPS When cut down it becomes a Cutback Elbow.

Concentric Reducer

Maintains a centerline straight through the pipe. A pocket is created in which liquid can remain stagnant.

Piping Materials Stainless Steel Pipe

Most common in corrosive service or high temperature service. Type 304 (18-8 SS) is 18% Chromium and 8% Nickel is the most common pipe required.

Piping Materials Carbon Steel Pipe

Most common. Galvanized has a thin coating of zinc. Black Pipe (Black Iron Pipe) is non-galvanized.

Single Line Drawings

Shows the layout for welded pipe fabrications. Represents the center of the pipe and the center of the fittings. Usually an orthographic view. Most common. Takes up less space.

Double Line Drawings

Shows the outside diameter of the pipe and fittings. Easier to read and visualize but takes up more space and more time consuming to draw. Usually used for short section of pipe so the information can be communicated more clearly.

Advantages of a Welded Joint

Smoother inside surfaces which reduces the effects of erosion and corrosion. A weld joint is more economical. Safer, stronger and leak proof.

Piping Materials Copper Tubing

Used for steam, air and oil service. High corrosion-resistance value. Most common for steam tracing of pipe equipment. 3 types: Type K - underground plumbing and heating Type L - interior plumbing and heating Type M - waste, vent, interior drainage and low-pressure applications

Reducing Elbow Fitting

Used in substitute for a 90 degree elbow and a weld reducer. Long radius only. 1.5x NPS Advantage: reduces the cost of a fitting and a circumferential weld. Disadvantage: not adaptable to other uses.

Piping Materials Alloy Steel Pipe

Used when increased mechanical properties are required.

Eccentric Reducer

Used when the bottom of the pipe is to be maintained level.

Reducing Cross Fitting

Used when the run is larger than the 2 outlets.

Straight Cross Fitting

When 4 outlets are required. Not used often.