Surveying Confined Space Hazards

July 28, 2003
Effective hazard assessments provide the foundation for your confined space process. These planning tips can help improve the quality of your process.

by Craig Schroll, CSP

Confined space surveys are an important, early part of your overall confined space safety process. Most other portions of your safety process will build on the foundation of the survey. An effective survey and hazard assessment process provides a firm basis for the rest of your process.

Initial surveys are conducted to identify all of the confined spaces at your site and to prepare an inventory list of these spaces. The spaces on the list will then be classified according to type. Various approaches may be used. At a minimum, the spaces should be classified as permit-required or non-permit. You may additionally want to indicate those spaces that would be eligible for alternate procedures entries or reclassification.

For many spaces, these classifications will be obvious even before the more comprehensive hazard assessment has been completed. For example, a solvent tank is clearly a permit-required confined space. A detailed hazard assessment is not necessary to make this determination. For some spaces, these categorizations may need to be made after the hazard assessments are completed. You may even find that some of the areas on your initial list turn out to not be confined spaces.

Keep all of the documentation from this initial survey on file. You may have to justify your decisions in the future and having a written record of what you considered can be valuable.

The confined space inventory may be maintained in any of several formats. A written list will suffice. It is more useful to keep this list electronically. The simplest version of this approach is a word processor document or spreadsheet. It is also relatively easy to create a form in most word processors and this allows the addition of some beneficial features to your records. The best format may be a database. Maintaining your list in a database allows you to store more information in the same place as your list.

However you decide to maintain the records of your inventory and surveys, you should use a standard format for the information that is ideally user friendly. Remember that the ultimate user is intended to be the entry team. If you approach the survey and hazard assessment as a compliance exercise only, you will lose most of the benefit of the process. This information should also be readily accessible to all who may need it. OSHA 1910.146 requires a documented inventory of confined spaces.

Initial Surveys

Each individual space will need to be surveyed, and the hazards identified and assessed. An effective survey should identify all of the issues that may present hazards or create safety challenges during entries. OSHA 1910.146 requires hazard assessments only prior to entry. I believe that waiting until a space needs to be entered creates a piecemeal approach that will not serve your overall process well. Conducting the hazard assessments on all your spaces initially improves the effectiveness of you confined space process. These initial surveys will need to be supplemented at the time of first entries into the space. There are issues you may not be able to evaluate properly when the space is closed, such as specifics of the internal configuration.

With the ready availability of digital photography, it is often benefical to include photos with your hazard assessment. Photos that are typically useful include: overall photos of the space and surrounding area, access and entry ways, interconnections to the space, and other key hazard issues. If you maintain confined space records electronically, these photos can be imbedded with the record.

The initial portion of the survey should cover basic identifying information, including date of the survey, who completed it and a clear and specific identification of the space being evaluated. I recommend that spaces be given unique identifying numbers or alphanumeric codes. This helps ensure that one space is not confused with another. This approach is particularly important if there are many similar spaces within your facility. A specific location of the space and a brief description need to be included. This identifying information should be detailed enough so that a person from your organization can clearly identify the space being discussed in the survey. The description should provide information on the normal use of the space and what it usually contains. The number, type and location of entry points also should be indicated.


The inherent hazards of the space must be considered, as well as hazards present in the immediate vicinity of the space that may affect entry operations. We need to consider the typical work done in the space as well.

A detailed discussion of confined space hazards is beyond the scope of this article. Several categories of hazards should be considered:

  • Atmospheric issues (oxygen, flammable and toxic gases and/or vapors),
  • Contents (current, previous and residue of cleaning materials),
  • Potential energy,
  • Environment in the space,
  • Configuration of the space,
  • Nature of the work,
  • External hazards, and
  • Miscellaneous hazards (e.g. animals and insects, noise, radiation).

Hazards that are not inherent to the space must also be considered. For example, a batch process tank that normally contains flammable liquids may be cleaned between batches with a caustic chemical. Entries will occur after cleaning so the caustic may be more of an issue than the flammables. Another example: crews entering a utility vault during the winter may have to deal with ice over and around the opening. This hazard may not be obvious if you conducted your assessment in August.

Your hazard assessment must be thorough. Generally, entry crews will not identify new hazards beyond what you have identified in the survey. Crews should be trained to do hazard assessments at the beginning of their entry preparation process. Realistically, though, time pressures and other factors work against this being as comprehensive as we might hope. Be specific when possible in identifying hazards. General statements of broad possibilities are of little benefit in a hazard assessment.

If you have a mobile work force that enters a confined space on another organization's site, a process will need to be developed for work crews to complete hazard assessments as part of the process of preparing for the job.

If you are not intimately familiar with the space and associated processes, it is essential to talk with production people that work in the area to get an insight into the issues with the space. Even if you are familiar with the space and processes, discussing it with operating personnel will often provide beneficial insights. It is also helpful to discuss the space with individuals that have entered it previously.

Information on who usually enters the space and how often helps identify issues that will relate to training. The "who" clearly identifies audiences that will need training. Typically you may have entrants from maintenance, production and outside contractors. There may be additional groups within your organization that must be considered.

Experience Factor

How often the space is entered provides us with information about the experience level personnel will have with the space. Frequent entries usually indicate that the crew will have had the opportunity to hone their work procedures and practices which is an advantage. One disadvantage of frequent entries is that you are more likely to see short cuts come into play as people get too comfortable with the space. Infrequently entered spaces don't allow for the development of much field experience, which may work against us. The advantage is that the crew won't typically view the entry as routine so they may stay more focused on the safety issues.

Evaluate all external connections to the space. This will help identify issues that will need to be isolated during entry preparations.

If your organization takes advantage of the alternate procedure entry and/or reclassification permitted under OSHA 1910.146, the hazard assessment should determine whether the space is eligible for either of these approaches.

If you have an internal confined space rescue team, an additional component of the survey should look specifically at rescue issues. Involve the team in conducting this portion of the survey to ensure that the rescue perspective is included.

Surveys and hazard assessments should be updated periodically. A general review of all items should be conducted at least annually. If changes occur in your facility or processes, the affected spaces need to be reassessed immediately. Reports of issues from entry crews may also provide warning that a space needs to be reevaluated. For example, if your crew discovers a hazardous atmosphere in a space that does not usually contain one, the source of the hazard should be determined and the hazard assessment revised if necessary.

Effective hazard assessments provide the foundation for your confined space process. All major components of the process depend upon an understanding of the hazards. Your training, equipment, policy, procedures, rescue needs and other aspects of your approach to confined space safety must be based upon a thorough knowledge of the challenges your entry crews will face.

Craig Schroll is a certified safety professional and certified utility safety administrator. He has 30 years experience in safety and loss control activities. He is a frequent conference speaker, author and seminar leader. He founded FIRECON in 1980 with the mission of helping clients prevent, plan for and control emergencies. He may be contacted at [email protected].

To view or print a PDF file of a sample of a Confined Space Survey Form, click here.

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