API - RP 2207 REDLINE
Preparing Tank Bottoms for Hot Work
|Publication Date:||1 December 2007|
This recommended practice addresses only the safety aspects of hot work on petroleum storage tank bottoms. It discusses safety precautions for preventing fires, explosions and associated injuries. The term hot work, as used in this publication, is defined as an operation that can produce a spark or flame hot enough to ignite flammable vapors. API 2009 provides more in-depth information on safe hot work practices and its requirements are not duplicated here.
This recommended practice does not contain all safety precautions and procedures that may be required prior to, during, or after a specific hot work activity. All hot work should be performed in compliance with applicable national, state and local regulatory requirements and recognized industry practices. Work practices of concern for working on tank bottoms, include but are not limited to: confined space entry, lockout/tagout, atmospheric testing, ventilation, and requirements for use of PPE. ANSI/API 2015 and ANSI/API 2016 provide guidance for tank entry consistent with OSHA regulations noted in the Section 2 References. This recommended practice does not repeat the extensively detailed information provided in those documents. Some of the relevant OSHA regulations from 29 CFR part 1910 and 29 CFR 1926 are included in the references. It is the responsibility of each organization to review and comply with applicable legal requirements.
The scope of API 2207 does not include:
- guidance for compliance with safety or environmental regulations or codes.
- engineering specifications for tank construction or rebuilding (see API tank standards).
- specific guidance for repair of shop-fabricated tanks which is addressed by Steel Tank Institute SP031. These tanks include those built to UL 142, API 650 Appendix J, Steel Tank Institute aboveground tank standards, as well as others.
- specific guidance for tank entry (see ANSI/API 2015 and ANSI/API 2016).
- welding techniques, craft skills or qualification of welders (see referenced welding standards).
- normal "safe work" practices such as fall protection, PPE, slip/trip/fall etc.
- entry or work in inert environments (see API 2217A).
Concepts of Hazard and Risk
Hazards are properties of materials (or situations) with the inherent ability to cause harm. Flammability, toxicity, corrosivity, stored chemical or mechanical energy all are hazards associated with various industrial materials or situations. Risk requires exposure. A fire or hot surface can cause thermal skin burns or a corrosive acid can cause chemical skin burns, but these can occur only if there is contact exposure to skin. In an empty tank a floating roof represents a "stored mechanical energy" hazard which might fall on persons working underneath, and so must be properly secured to reduce risk of contact before performing entry work.
There is no risk when there is no potential for exposure.
Determining the level of risk involves understanding hazards and estimating the probability of exposure and severity of consequences that could lead to harm. While the preceding examples relate hazards to the risk to people, the same principles are valid for evaluating property risk. For instance, a flammable mixture of hydrocarbon vapors in air can ignite if exposed to a source of ignition, resulting in a fire that could damage property as well as injure people.
Relationship to Regulations
This recommended practice aims to share practices which over time have been useful in injury prevention programs. The specifics of compliance with either safety or environmental laws or regulations fall outside the scope of this standard, but should be carefully reviewed by those authorizing and conducting work.
General INTRODUCTION This publication outlines safety
precautions for preventing accidental fires and explosions when hot
work is performed on tank bottoms. The term hot work, as used in
this publication, is defined as an operation that can produce a
spark or flame hot enough to ignite flammable
vapors. This publication may not contain
all safety precautions and procedures that may be required prior to
or during a specific hot work activity. All hot work should be
performed in compliance with applicable national, state and local
regulatory requirements and recognized industry practices,
including but not limited to: confined space procedures,
lockout/tagout procedures, and requirements for personal protective
equipment (see OSHA Regulations 29 CFR part 1910 and API
publications 2015 and 2217). Tanks that have contained flammable or
combustible liquids, regardless of their age and type of
construction, must be considered unsafe for hot work until approved
by safety inspections. These inspections include gas testing to
determine if the oxygen content of each tank is between 19.5 and
22.5 percent. Special techniques are required in the performance of
hot work on tank bottoms to prevent the ignition of flammable
vapors that may be trapped under the tank. Although each repair of tank
bottoms must receive careful consideration, the safety procedures
described in this publication provide various methods for preparing
tank bottoms for hot work. These procedures will apply to most