Pigging Valves

Pigging Valves – Comprehensive Overview

Overview

A Pigging Valve is an integrated device combining the functions of a pig launcher/receiver and a valve. It is widely used in crude oil, refined products, natural gas, and chemical pipeline systems for pipeline cleaning, internal inspection, and maintenance without dismantling the pipeline.
Compared to traditional pig launchers and receivers, pigging valves are compact, space-saving, and allow fast pig launching or receiving, improving operational safety and efficiency.

Key functions:

• Launching or receiving pipeline pigs

• Removing deposits such as wax, scale, or rust from pipeline interiors

• Supporting in-line inspection pigs for pipeline integrity assessment

• Reducing operational footprint and installation cost

Working Principle

The pigging valve has a specially designed internal chamber and switching mechanism. When open, the valve aligns the pig chamber with the pipeline bore, allowing the pig to enter or exit the line. When closed, the chamber is isolated from the pipeline, enabling safe loading or removal of the pig.

Basic operating steps:

1. Launching:

   • Close valve → Load pig into chamber → Close cover → Open valve → Pipeline pressure pushes pig into the line.

2. Receiving:

   • Pig arrives in valve chamber → Close valve → Depressurize chamber → Open cover → Remove pig.

Types of Pigging Valves

1. Rotary Pigging Valve – Uses a rotating plug or ball to align chamber and pipeline.

2. Sliding Pigging Valve – Internal slide mechanism to connect/disconnect chamber from pipeline.

3. Spherical Pigging Valve – Pig is housed in a grooved ball inside the valve body.

4. Combined Type – Hybrid designs integrating conventional pig trap features.

Structural Features

• Integrated design: Combines pig launcher/receiver and isolation valve

• Quick operation: Fast pig loading/unloading

• Full-bore design: Ensures smooth pig passage without obstruction

• High sealing performance: Soft or metal-to-metal sealing options

• Safety features: Built-in pressure relief to avoid opening under pressure

• Material adaptability: Available in carbon steel, stainless steel, duplex steel, alloy steel, etc.

• Corrosion and wear resistance: Designed for harsh service conditions

Structural Diagram (Typical Components)

• Valve cover

• Pig chamber

• Main pipeline bore

• Valve body

• Seals

• Pressure relief valve

• Guide and support structure for pig

Standards and Specifications

Design & Manufacturing:

• API 6D, ASME B16.34

Dimensions:

• ASME B16.5, ASME B16.47 (flanged ends)

• API, EN, or ISO dimensional series

Pressure Testing:

• API 598, API 6D

Welding Requirements:

• ASME Section IX, API 1104

Material Standards:

• ASTM, EN, ISO equivalent grades

Coating & Corrosion Protection:

• ISO 12944

• NACE MR0175 / ISO 15156 (for sour service)

Material Selection & Service Applications

Installation, Operation & Maintenance

Installation Guidelines:

• Install in straight pipeline sections with sufficient clearance for pig insertion/removal.

• Ensure alignment between valve bore and pipeline axis.

• Use flanged or welded connections as specified.

• Clean pipeline before installation to avoid damage to seals.

Operating Procedures:

• Follow launch/receive steps strictly, ensuring chamber is depressurized before opening cover.

• Verify pig dimensions match the pipeline ID.

Maintenance:

• Regularly inspect seals and moving parts for wear.

• Check pressure relief valve operation.

• Apply anti-corrosion grease during long-term shutdowns.

• Use compatible lubricants for the sealing system.

Pig Selection Guidelines