What Is ASME B31.4

Asme B31.4: Liquid Transportation Systems For Hydrocarbons, Liquid Petroleum Gas, Anhydrous Ammonia, and Alcohols

ASME B31.4, a section of the ASME Pressure Piping Code, outlines the standards for designing, selecting materials, constructing, assembling, inspecting, and testing pipelines that transport liquids. These include crude oil, condensate, natural gasoline, natural gas liquids, liquefied petroleum gas, liquid alcohols, anhydrous ammonia, and various petroleum products. The code applies to pipelines connecting production sites, tank farms, gas processing facilities, refineries, pumping stations, ammonia plants, terminals, and other receiving or delivery locations.

ASME B31.4 is a recognized pipeline standard created by the American Society of Mechanical Engineers (ASME). It provides detailed requirements for the design, construction, inspection, testing, operation, and upkeep of liquid pipeline systems. These systems usually carry crude oil, refined petroleum products, liquefied petroleum gas (LPG), carbon dioxide (CO₂), and other liquid substances that may be hazardous or non-hazardous.

The main purpose of ASME B31.4 is to ensure that pipelines are built and maintained with the highest levels of safety, reliability, and efficiency. It applies to both new pipeline installations and the continued service of existing ones. The code covers several important aspects, such as:

• Material requirements – ensuring pipeline materials are suitable for strength and resistance to damage.
• Welding and fabrication practices – establishing safe methods for joining and constructing pipelines.
• Pressure design limits – defining stress and thickness requirements to prevent failures.
• Testing and inspection procedures – including hydrostatic testing to verify pipeline integrity.
• Operational safety and maintenance – offering guidance for monitoring, repairs, and safe long-term use.

In essence, ASME B31.4 serves as a safeguard for industries and communities by reducing risks associated with transporting liquids through pipelines. It is widely adopted in the oil, gas, chemical, and energy sectors, making it an essential code for safe pipeline operations.

Detailed Scope of ASME B31.4

The ASME B31.4 standard not only addresses the design and construction of liquid pipelines but also clearly defines the facilities and systems it governs. Its scope covers the following areas in detail:

Pipeline Terminals and Auxiliary Facilities

The code applies to both primary pipelines and auxiliary piping systems that handle liquid petroleum and liquid anhydrous ammonia at key transfer points. These include marine terminals, rail and truck loading facilities, tank farms, pump stations, pressure-reducing stations, and metering stations. It also encompasses equipment such as scraper traps, strainers, and prover loops, which are essential for cleaning, measuring, and ensuring smooth flow within the pipeline.

Storage Systems

ASME B31.4 also extends to storage and working tanks, including specialized pipe-type storage fabricated from piping components. The code covers the interconnecting piping networks that link these tanks and facilities to the larger pipeline system.

Plant-Based Piping Installations

The standard includes liquid petroleum and liquid anhydrous ammonia pipelines that are located within designated areas of refineries, natural gasoline plants, gas processing plants, ammonia facilities, and bulk storage plants. Only those parts of the property specifically reserved for pipeline operations fall under this scope.

Operation and Maintenance Requirements

Beyond design and construction, ASME B31.4 emphasizes safe operation and maintenance practices. It addresses measures to safeguard the general public, operating personnel, surrounding environment, property, and the integrity of the piping system itself.

Exclusions from ASME B31.4

The ASME B31.4 standard does not apply to certain systems and equipment outside its intended scope. These exclusions include:

• Auxiliary service lines such as those used for water, air, steam, lubricating oil, gas, or fuel.
• Process equipment including pressure vessels, heat exchangers, pumps, meters, and other machinery, along with their internal piping.
• Low-pressure piping designed to operate at internal pressures of 15 psi (100 kPa) or less, regardless of the operating temperature.
• High- or low-temperature systems operating at pressures above 15 psi (100 kPa) but with design temperatures below -20°F (-29°C) or above 250°F (120°C).
• Oilfield piping and equipment, including casing, tubing, wellhead assemblies, oil and gas separators, crude oil tanks, production facilities, and the pipelines connecting these installations.
• Refinery, natural gasoline, gas processing, ammonia, and bulk plant piping, except where specifically included under the code’s defined scope.
• Gas transmission and distribution lines, which are covered under other ASME standards.
• Proprietary equipment or instruments, where design and fabrication fall outside the scope of this code, unless otherwise restricted.
• Ammonia refrigeration piping systems, which are governed by ASME B31.5 (Refrigeration Piping Code).
• Carbon dioxide gathering and distribution systems in the field.

The exclusions emphasize that ASME B31.4 is focused on liquid petroleum and anhydrous ammonia pipelines, while ensuring safety for the public, operating personnel, the environment, and the pipeline system itself.

Asme B31.5: Refrigeration Piping

This section of ASME B31, Pressure Piping Code, contains requirements for the materials, design, fabrication, assembly, erection, testing, and inspection of refrigerant and secondary coolant piping for temperatures as low as -320°F (-195.5°C), except when other sections of the code cover requirements for refrigeration piping.

ASME B31.5 does not apply to the following

• Self-contained or unit systems subject to the requirements of Underwriters’ Laboratories (UL) or other nationally recognized testing laboratories.

• Water piping.

• Piping designed for external or internal gauge pressure not exceeding 15 psig (100 kPa).