310101d Pipe Threading and Joints

Objectives

  • Identify Different Types of Pipe

    • Types, sizes of pipe, fittings, and flanges.

  • Explain Tools Used in Joining

    • Tools involved in the process of pipe joining.

  • Achieving Installation

    • Installation of threaded pipe joints.

  • Identify Hazards

    • Hazards related to pipe and fitting selection and installation.

General Overview of Pipe

  • Pipe: Hollow structure for containing process flow.

  • Description of pipe includes:

    • Materials

    • Grades & schedules

    • Pressure ratings

    • Size (Outer Diameter - OD)

    • Finishes

Types of Pipe Materials

Ferrous Pipe

  • Definition: Any pipe containing iron ore.

Non-Ferrous Pipe

  • Definition: All other pipe materials without iron ore.

  • Examples include:

    • Aluminum

    • Copper

    • Brass

    • Bronze

    • Glass

    • Lead

    • Plastics (ABS, PVC, PE, Fiberglass)

Ferrous Pipe Characteristics

  • First known ferrous pipe: Pig iron (high carbon content, brittle).

  • Current materials:

    • Mild steel (0.1 to 0.2% carbon)

    • Cast Iron (1.8% carbon)

    • Carbon Steel (<1.7% carbon, <1.65% manganese)

    • Alloy Steel (specific amounts of iron, carbon, manganese, silicon, chromium, nickel, molybdenum).

  • Creep: Tendency of metals to deform permanently under mechanical stress.

Grades and Schedules

  • Historical terminology for pipe grades:

    • Standard (STD): Schedule 40.

    • Extra Strong (XS): Schedule 80.

    • Double Extra Strong (XXS): Above Schedule 160.

  • Measurement basis: Nominal pipe sizes measured by OD.

Schedule Comparisons

  • Wall thickness increases for stronger ratings:

    • Light Wall: Schedule #10

    • Standard: Schedule #40

    • Extra Strong: Schedule #80

    • Extra Extra Strong: Schedule #160

  • Example of dimensions:

    • Outside Diameter: 1.315 in.

    • Inside Diameter varies based on schedule.

Pipe End Finishes

  • Types of finishes:

    • Plain: Squared end, reamed.

    • Threaded: Standard taper or coupled, straight parallel (not for installations).

    • Beveled: Suitable for welding.

    • Grooved: Compatible with grooved couplings.

Pipe Fitting Classes

Malleable Iron Class 150 (Standard)

  • Applications: Gas & Air lines (NPS 1/8 to NPS 6).

  • Pressure and Temperature Ratings:

    • Liquids: 2078 kPa (300 psi) @ 66°C (150°F).

    • Steam: 1034 kPa (150 psi) @ 66°C (150°F).

    • Gas: 860 kPa (125 psi) @ 66°C (150°F).

Malleable Iron Class 300 (Extra Heavy)

  • Applications: Steam (NPS 1/4 to NPS 3).

  • Pressure and Temperature Ratings:

    • Steam: 2070 kPa (300 psi) @ 288°C (550°F).

    • Liquids & Gas: Up to 13790 kPa (2000 psi) @ 66°C (150°F).

Flanges Overview

  • Types of flanges:

    • Weld Neck Flange

    • Threaded Flange

    • Flat Flange

    • Socket Welding Flange

    • Blind Flange

    • Slip-On-Welding Flange

Flange Tightening Sequence

  • Importance of proper torque:

    • Specify number of bolts and tightening order (e.g. 4-bolt, 12-bolt sequences).

Gaskets

Spiral-Wound Gaskets

  • Specifications include:

    • Manufacturer

    • Size

    • Pressure rating

    • Winding material and filler.

Ring Type Joint Gaskets

  • Types: Oval, Octagonal.

  • Identification marked on ANSI standard gaskets.

Flange and Gasket Summary

  • Key considerations for selection:

    • Pressure

    • Temperature

    • Chemical properties

    • Mechanical stress

  • Recommendation: Replace like for like.

  • Torque application: Progressive and in sequence.

Pipe Threading Methods

  • NPT (American Standard Pipe Taper Thread):

    • Measurement: ¾” taper per foot.

  • Two types of threads:

    • Tapered Thread: Seal from metal-to-metal wedging.

    • Straight Thread: Seal using O-ring or bonded washer.

Pipe Threading Procedure

  1. Measure.

  2. Mark and cut.

  3. Ream the pipe.

  4. Oil and thread.

  5. Clean and apply jointing compound or TFE tape.

  6. Apply fitting and tighten.

Measurement for Pipe Cutting and Threading

  • Methods:

    • End to end measurement.

    • Center to center measurement.

  • Fitting allowances important for accurate connections (Throw vs. TE calculations).

Pipe Tightening Table

  • Reference table outlines:

    • Nominal sizes

    • Thread counts

    • Length cut

    • Approximate engagement.

NPT Pipe Size and Schedule Ratings

  • Typical dimensions for schedules (10, 40, 80, 160).

  • Example of dimensions and thickness ratings for common sizes.

Pipe Cutter and Use

  • Use proper tightening techniques for specific pipe materials.

  • Safety considerations: Avoid spiral reamers on power threaders to prevent accidents.

Self-Test and Review

  • Complete self-test: Understand key topics for mastery in ILM 310101D.