IPE-TM-810-01

Table of Contents

List of Figures

Purpose

This procedure provides guidelines for indicating pipe class breaks as required on Inflection Point Engineering Piping & Instrument Diagrams (P&IDs).

General

P&IDs are developed from modules, most of which include pipe classes and class breaks for a given set of conditions such as equipment design pressures and temperatures, materials, corrosion allowances and NACE requirements. However, pipe classes are subject to change as different design conditions are introduced from one project to another, which requires re-evaluating the suitability of pipe classes and their associated pipe class breaks. The guidelines in this procedure will help maintain a high level of consistency regarding the selection of proper pipe class breaks on the P&ID. These guidelines are to be followed during the P&ID review and when preparing the Inflection Point Engineering Project Specification 801. These guidelines provide additional information with schematic details that help identify pipe class breaks and their locations.

General Consideration

Termination of Lines

In general, lines terminate at equipment. Additionally, process conditions may dictate that lines with valves, blankoffs and pairs of flanges would require a pipe class break.

Criteria for Determining Pipe Class Breaks

The criteria for determining pipe class breaks are set by process and metallurgical requirements based upon design pressures, design temperatures, flange classes, materials, corrosion allowances and any other pertinent information found in the Material Selection Diagram (MSD), Project Specifications and BEDQs.

Glossary

Main Line

A primary line that carries only the main flow.

A primary line that carries the main flow that other lines can branch either to or from.

Branch Line

A secondary line that carries flow away from the main line.

Connecting Line

A secondary line that carries flow from another source towards the main line.

Continuous Flow

An uninterrupted flow during normal operation.

Intermittent Flow

An occasional flow during normal operation or during special regeneration, startup, heating, cooling, etc.

Last Block Valve

The last valve in the direction of flow (e.g., gate, globe, check or control valve).

Junction

A connection between two lines, e.g. a connection between a branch line and a main line.

Higher Alloy Material

A material that contains a higher percentage of alloying elements than the material to which it is compared, e.g. stainless steel to 1¼ Cr – ½ Mo.

Lower Alloy Material

A material that contains a lower percentage of alloying elements than the material to which it is compared, e.g. 1 1/4 Cr - 1/2 Mo to stainless steel.

Alloy Material Ranking

For the purpose of qualifying higher alloy materials vs. lower alloy materials, Inflection Point Engineering establishes an alloy materials ranking table:

Killed carbon steel (KCS) lower Alloy

3 1/2 Nickel

1 1/4 Cr-1/2 Mo

2 1/4 Cr-1/2 Mo

5Cr-1/2Mo

9Cr

304/304L stainless steel

316/316L stainless steel

321/347 stainless steel

Alloy 400

Alloy 825

Alloy 625

Hastelloy™ higher Alloy

Higher Flange Class

A flange class that is of a higher structural strength than the class to which it is compared to, e,g, ASME Class 300 to ASME Class 150.

Lower Flange Class

A flange class that is of a lower structural strength than the class to which it is compared to, e.g, ASME Class 150 to ASME Class 300.

Applicable Flange Classes

Applicable ASME Flange Classes are as follows:

ASME Class 150, 300, 600, 900, 1500 and 2500

Pipe Class Break Designation

This indicates a change between two pipe classes.

Pipe Class Breaks – Typical Examples

Main Lines

Evaluate 10/13 rule for low pressure side of exchangers

Figure 1 No valve between equipment - same flange class

Evaluate 10/13 rule for low pressure side of exchangers.

Figure 2 No valve between equipment – different flange class

The main line must retain its pipe class up to and including the last block valve in the direction of flow. Evaluate 10/13 rule for low pressure side of exchangers.

Figure 3 Control valve assembly between equipment - different flange class

The main line must retain its pipe class up to and including the last block valve in the direction of flow.

Figure 4 Last block valve between equipment – different flange class

The main line must retain higher pipe class from the equipment to the battery limits and beyond.

Figure 5 Battery Limit (valve at the end of the process area)

The main line must retain the pipe class from the last block valves upstream of the equipment.

Figure 6 Feed line to process equipment

Branch Line

Evaluate 10/13 rule for low pressure side of exchangers.

Figure 7 No valve between main line and equipment – different flange class, same materials, continuous or intermittent flow.

The branch line must retain the same pipe class as the main line, in the direction of flow up to and including the last block valve.

Figure 8 Last block valve – different flange class, same materials, continuous or intermittent flow.

The branch line must retain the same pipe class as the main line to and including the blankoff.

Figure 9 Blankoff beyond the last block valve – different flange class, same materials, intermittent flow

The branch line must retain the same pipe class as the main line to and including the last valve.

Figure 10 Junction – same flange class, different materials, continuous flow

The branch line must retain the same pipe class as the main line to and including the blankoff.

Figure 11 Blankoff – same flange class, different materials, intermittent flow

Connecting Line

Higher rated connecting lines must retain their own pipe class as indicated below.

Figure 12 Different flange class, same materials, continuous or intermittent flow

Lower rated connecting lines must retain their own pipe class as indicated below.

Figure 13 Different flange class, same materials, continuous or intermittent flow

The connecting line must retain its own pipe class up to and including the last valve.

Figure 14 Junction – same flange class, different alloys, continuous or intermittent flow

Figure 15 Same flange class, different alloy, continuous or intermittent flow

Figure 16 Different flange class, different alloy, continuous or intermittent flow

Figure 17 Different flange class, different alloy, continuous or intermittent flow

Figure 18 Different flange class, different alloy, continuous or intermittent flow

Figure 19 Blankoff during normal operation

Figure 20 Blankoff when not in use

Process Specific Pipe Class Breaks

Figure 21 Combined Feed Exchanger

Figure 22 Combined Feed Exchanger – check valve in the feed line

Figure 23 Combined Feed Exchanger – no check valve in the feed line

Figure 24 Separator

Figure 25 Inflection Point Engineering Penex and Butamer Process – inlet to Net Gas Scrubber

Figure 26 Amine Treating Process Unit - inlet to Amine Stripper

Figure 27 Chemical Injection – protection of pump internals

Figure 28 Steam turbine driven pump – pressure relief valve present

Figure 29 Steam turbine driven pump – no pressure relief valve

Figure 30 General Application

Figure 31 Turbine Application – Unicracking, FCC Power Recovery Unit

Figure 32 High Pressure Storage Tank application - presence of pressure regulator

Figure 33 Centrifugal Pumps - suction line flange class upgrade

No pressure pipe class break required. Stainless steel piping is not required for caustic pumps.

Figure 34 Proportioning Pumps Application – Suction and Discharge of same Flange Class

Figure 35 Proportioning Pumps Application – Suction and Discharge of different Flange Class

Figure 36 Centrifugal and Reciprocating Compressor (two stage compressor shown)

Figure 37 High Pressure Combined Feed Exchanger – bypass

The line between the heat exchanger and the vessel must retain its higher flange class.

Figure 38 Distributor Inlet Line from Higher Pressure Exchanger

Figure 39 ASME SECT. I piping around steam generator

Figure 40 Desuperheater Piping

Figure 41 Nitrogen Purge Piping to Equipment Vent Line

Figure 42 Quench Gas to Reactor – Same Flange Class

Figure 43 Quench Gas to Reactor – Different Flange Class