Technical Bulletin 118 (TB118) - A Comprehensive Guide

Technical Bulletin 118 - Registered Gas Engineer

Gas safety is paramount in the United Kingdom, and the Gas Safe Register plays a central role in ensuring that gas engineers and professionals have access to the most up-to-date technical guidance and information. One of the essential documents provided by the Gas Safe Register is Technical Bulletin 118 (TB118). This technical bulletin offers comprehensive guidance on various critical aspects of gas installations. In this detailed guide, we will delve into the specifics of TB118, covering its purpose, key technical details, and relevance to gas engineers and the gas industry as a whole.

Understanding TB118 - What It Is and Why It Matters

Technical Bulletin 118 - Registered Gas Engineer

The Significance of TB118

Technical Bulletin 118 (TB118) is a crucial document issued by the Gas Safe Register. It serves as a valuable resource for gas engineers, professionals, and individuals responsible for gas installations. The primary objective of TB118 is to provide detailed technical guidance on various aspects of gas work, promoting safety and compliance with industry standards.

Key Focus Areas of TB118

TB118 addresses a range of technical issues within gas installations, ensuring that gas engineers have access to vital information and procedures. Some of the key focus areas covered by TB118 include:

1. Gas Pipe Sizing

One of the fundamental aspects of gas installations is determining the correct size of gas pipes. TB118 provides comprehensive guidance on how to calculate the appropriate pipe size to ensure a safe and efficient gas supply to appliances. It outlines the factors, calculations, and considerations involved in this crucial process.

2. Flue and Ventilation

Proper flue and ventilation systems are essential to ensure the safe operation of gas appliances. TB118 offers detailed guidance on the design, installation, and maintenance of flues and ventilation, with a focus on preventing the buildup of harmful combustion gases and ensuring an adequate air supply.

3. Combustion Analysis

TB118 emphasizes the significance of combustion analysis in gas work. It provides instructions on how to perform accurate combustion analysis to assess appliance efficiency and safety. This involves measuring various parameters such as carbon monoxide levels, oxygen content, and flue gas temperature.

4. Safe Operation and Maintenance

Maintaining gas appliances is crucial for their continued safe and efficient operation. TB118 underscores the importance of regular maintenance and servicing of gas appliances, outlining best practices for gas engineers to follow.

5. Industry Standards and Regulations

Gas engineers must adhere to industry standards and regulations when carrying out gas work. TB118 references and explains the relevant standards, ensuring that gas professionals are aware of the legal requirements and safety guidelines.

Technical Bulletin 118 - Registered Gas Engineer

Who Should Refer to TB118?

TB118 is a valuable resource for several key stakeholders in the gas industry:

  • Gas Engineers: Gas engineers rely on TB118 to ensure their work aligns with safety standards and regulations. It equips them with the necessary technical details to conduct gas installations, repairs, and maintenance safely and efficiently.

  • Gas Safe Registered Businesses: Businesses operating in the gas industry use TB118 to train and educate their workforce on best practices and technical requirements, fostering a culture of safety and compliance.

  • Gas Appliance Manufacturers: Manufacturers of gas appliances refer to TB118 when designing and testing their products to ensure they meet safety and performance standards.

Specific Technical Details in TB118

Gas Pipe Sizing

TB118 provides comprehensive guidance on gas pipe sizing, detailing the calculations and considerations involved. Key factors covered include:

  • The type of gas being supplied (e.g., natural gas or LPG).
  • The maximum gas demand of each appliance.
  • Pipe material and length.
  • Pressure drop calculations.
  • Allowable pressure drop limits.

By following the guidelines in TB118, gas engineers can accurately determine the size of gas pipes required for safe and efficient gas supply.

Flue and Ventilation

Proper flue and ventilation systems are critical for preventing the buildup of combustion gases, such as carbon monoxide. TB118 offers guidance on:

  • Flue design and sizing, including the selection of appropriate flue materials.
  • Ventilation requirements to ensure an adequate air supply for combustion and appliance operation.
  • Clearances and distances for flue termination points to avoid potential hazards.

Combustion Analysis

TB118 outlines the essential steps for performing combustion analysis, including:

  • Measuring carbon monoxide (CO) levels to assess combustion efficiency and safety.
  • Monitoring oxygen (O2) content to determine the completeness of combustion.
  • Checking flue gas temperature to identify potential issues.

This analysis helps gas engineers verify appliance performance and make necessary adjustments.

Safe Operation and Maintenance

TB118 emphasizes the importance of regular appliance maintenance and servicing, including:

  • Cleaning and inspecting gas appliances to ensure they operate efficiently.
  • Checking for leaks and addressing any issues promptly.
  • Replacing faulty or worn components as needed.
  • Conducting safety checks to verify the correct operation of safety devices and controls.


Technical Bulletin 118 (TB118) is an invaluable resource that promotes gas safety in the UK. Gas engineers, businesses, and manufacturers depend on its technical guidance to ensure the safety and compliance of gas installations. By adhering to the specific details outlined in TB118, gas professionals play a pivotal role in maintaining the highest standards of gas safety across the country. Regular reference to TB118 is essential to stay updated on the latest technical information and best practices in the field of gas engineering, ultimately contributing to safer gas installations and enhanced gas safety standards.

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Technical Bulletin 118 - Gas Safety FAQ

Technical Bulletin 118 (TB118) is a document issued by the Gas Safe Register. It provides detailed technical guidance to gas engineers and professionals in the United Kingdom, offering information on various aspects of gas work and safety.

TB118 is not Gas Safe itself but is issued by the Gas Safe Register. It contains valuable technical information and guidance that gas engineers use to ensure safe and compliant gas installations.

TB118 provides guidance on several crucial aspects of gas work, including gas pipe sizing, flue and ventilation systems, combustion analysis, and safe operation and maintenance of gas appliances.

Safe isolation of gas involves locating the Emergency Control Valve (ECV), turning off the gas, verifying isolation, and then carrying out the required work safely. Always use the proper gas shut-off tools and follow safety protocols.

Gas engineers can access Technical Bulletin 118 and other technical service bulletins by visiting the official Gas Safe Register website or contacting Gas Safe directly.

The purpose of a technical bulletin is to provide gas engineers with up-to-date technical information, guidance, and best practices to ensure safety and compliance in their gas work.

A gas safe inspection typically involves a comprehensive assessment of gas appliances, pipework, and ventilation systems to ensure they meet safety standards. This may include checks for leaks, proper operation, adequate ventilation, and compliance with regulations.

A Gas Safe test refers to the inspection and assessment of gas installations and appliances to ensure they are safe, compliant, and in good working condition.

Gas Safe is the official register of gas engineers and businesses in the UK. It ensures that gas engineers meet high standards of competence and safety, protecting both consumers and professionals.

A gas safety check primarily focuses on gas appliances, pipework, and ventilation. While radiators themselves are not typically checked, the inspection may include ensuring that any gas-fired central heating systems are safe and properly vented.

Yes, it is illegal to sell a house in the UK without a valid Gas Safety Certificate. This certificate confirms that gas appliances and installations in the property meet safety standards.

A plumber can perform a gas safety check only if they are Gas Safe registered. Gas Safe registration is required for anyone conducting gas work in the UK.

The Gas Safe Register includes thousands of gas engineers and businesses throughout the UK, all of whom have demonstrated their competence and safety in working with gas.

You can verify if an engineer is Gas Safe registered by checking their Gas Safe ID card, which displays their registration details and expiration date.

Gas Safe registration typically lasts for one year. Gas engineers must renew their registration annually by completing required assessments and continuing their professional development.

"BR" on the Gas Safe Register likely stands for "Business Registration," indicating that the individual or entity is registered as a gas business with multiple engineers under its management.

The Gas Safe Register is managed and operated by Capita Gas Registration and Ancillary Services Limited on behalf of the Health and Safety Executive (HSE) in the United Kingdom.

Yes, gas engineers are required to pay an annual registration fee to maintain their Gas Safe registration. This fee covers the costs associated with registration, competency assessments, and ongoing monitoring to ensure gas safety.

Yes, you can obtain a copy of your Gas Safe certificate online by logging into your Gas Safe account on the official Gas Safe Register website. The certificate provides evidence of your Gas Safe registration and competence to work with gas.

Gas Safe registration typically requires annual renewal. Gas engineers must renew their certification each year to demonstrate ongoing competence and compliance with safety standards.

Homeowners should arrange a Gas Safety Certificate inspection annually to ensure the safety and proper operation of gas appliances. It is a legal requirement for landlords to obtain an annual Gas Safety Certificate for rental properties. Please note that the information provided in this FAQ is for general reference and informational purposes. Specific queries related to gas safety, technical bulletins, or Gas Safe registration should be directed to the Gas Safe Register or a qualified professional.

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