Case Studies » Case Study 5: Sour Water Pipeline Repairs

At a chemical plant, there are two lines carrying "sour water" (water contaminated with hydrocarbons, hydrogen sulfide, or other chemicals). The lines run between the facility's sour water stripping unit and its tank farm where the processed sour water is stored.

A group of maintenance employees is assigned to replace orifice plates in two lines running between the sour water stripping unit and the tank storage farm. One plate is in the line running into the tank storage farm; the other is in the return line. To perform this operation, eleven valves need to be isolated: nine at the sour water stripping unit, and two at the tank storage farm. The tank storage farm is located more than a half-mile from the sour water stripping unit. Because there is no written procedure for this particular operation, the operator issuing the work permit for the orifice plate removals at the sour water stripping unit prepares a supplemental blanking and tagging list in order to identify all energy isolation points. After completing the list, the operator ensures that all nine isolation points within the operational limits of the sour water stripping unit are isolated, blanked, locked, and tagged. Following this step, the two valves at the tank storage farm (the receive and return lines) must be isolated before the lockout/tagout is complete and the permit can be issued.

The sour water stripping unit operator telephones the tank farm operator and requests that both the receive and the return sour water valves be locked out at the tank servicing the sour water stripping unit. The tank farm operator calls back and confirms that lockout is accomplished. No one, however, verified lockout or hung a tag on the two valves at the tank storage farm. The employees took receipt of the permit and commenced work on the orifice plates. Although the tank farm operator indicated he had locked out both of the valves at the tank farm, he had apparently failed to lockout the return sour water valve. Because the line was not isolated at the tank farm, when the employees opened a flange at the site of the orifice plate in the return line, they were exposed to a stream of sour water. An incident report was completed by the employer.

OSHA's investigation discloses that there are no specific procedures for isolating either of the orifice plates, and that a work authorization permit was used. Since the employer has no requirement for retaining blanking and tagging lists once a job is completed, the specific steps taken that led to this incident could not be identified. The work authorization permit form simply had a box checked to indicate that all valves were blocked and locked. The inspection also revealed that the operators of the sour water stripping unit and tank storage farm were trained only to a level of an "affected employee" under the Lockout/Tagout standard.

The employer's lockout/tagout program requires that the permit issuer accompany the permit receiver to the lockout locations listed on the blanking and tagging list and that the receiver verify that lockout is performed by hanging a craft tag on the locked equipment. The permit receiver's lock is then to be attached to the operator's lockbox containing all the keys used to secure the equipment, if applicable.

Question 1

Is the employer required to develop specific written procedures for this sour water pipeline orifice plate replacement task?

  • Correct.

    The energy control procedure provisions require the documentation of procedures that clearly and specifically outline elements described in 29 CFR 1910.147(c)(4)(ii). Because of the need to follow specific steps to successfully lockout a machine or piece of equipment as illustrated by this incident, a documented procedure is necessary for most energy control situations.

  • Incorrect.

    The energy control procedure provisions require the documentation of procedures that clearly and specifically outline elements described in 29 CFR 1910.147(c)(4)(ii). Because of the need to follow specific steps to successfully lockout a machine or piece of equipment as illustrated by this incident, a documented procedure is necessary for most energy control situations.

Question 2

Would this employer's use of a work authorization permit and generic energy control procedure satisfy the requirement for a specific written energy control procedure?

  • Incorrect.

    This employer failed to meet the requirements of 29 CFR 1910.147(c)(4)(ii). The work authorization permit was overly vague in that the energy isolation points were not identified on the permit and the specific procedures outlined in their generic hazardous energy control procedure were not implemented. The employer may use a work authorization permit in conjunction with a generic hazardous energy control procedure if the permit identifies the equipment to be serviced, the types and unique energy characteristics to be encountered, specific energy isolation points, methods for safe work, and the process or procedures to be used to accomplish the task.

    For more information: Refer to Work permits in lockout/tagout standard requirements, for further details.

  • Correct.

    This employer failed to meet the requirements of 29 CFR 1910.147(c)(4)(ii). The work authorization permit was overly vague in that the energy isolation points were not identified on the permit and the specific procedures outlined in their generic hazardous energy control procedure were not implemented. The employer may use a work authorization permit in conjunction with a generic hazardous energy control procedure if the permit identifies the equipment to be serviced, the types and unique energy characteristics to be encountered, specific energy isolation points, methods for safe work, and the process or procedures to be used to accomplish the task.

    For more information: Refer to Work permits in lockout/tagout standard requirements, for further details.

Question 3

Would the blanking and tagging list be a required component of the employer's energy control procedure?

  • Correct. A blanking and tagging list is a required component in this case.

    The employer's energy control program required the use of a blanking and tagging list to identify specific isolation points as part of the work authorization permit system. As a result, the blanking and tagging list is an integral part of, and must accompany, the work authorization permit. In this case study, the employer used a blanking and tagging list; however, the employer failed to maintain documentation of this list to ensure consistent and safe application of the energy control procedure.

    Moreover, failing to retain the list will prevent an effective periodic inspection of the lockout procedure.

  • Incorrect. Actually, a blanking and tagging list is a required component in this case.

    The employer's energy control program required the use of a blanking and tagging list to identify specific isolation points as part of the work authorization permit system. As a result, the blanking and tagging list is an integral part of, and must accompany, the work authorization permit. In this case study, the employer used a blanking and tagging list; however, the employer failed to maintain documentation of this list to ensure consistent and safe application of the energy control procedure.

    Moreover, failing to retain the list will prevent an effective periodic inspection of the lockout procedure.

Question 4

Would group lockout/tagout requirements apply to the piping service and maintenance work described in this example?

Question 5

Has the employer met the requirements for verification of isolation?

  • Incorrect. Here, the employer has not met the requirements.

    Prior to the start of work, the authorized employees did not personally verify the isolation of the two sour water valves at the tank farm, as required by 29 CFR 1910.147(d)(6) and (f)(3)(ii)(D).

  • Correct. The employer has not met the requirements.

    Prior to the start of work, the authorized employees did not verify the isolation of the two sour water valves at the tank farm, as required by 29 CFR 1910.147(d)(6) and (f)(3)(ii)(D). The employer may designate a primary authorized employee to verify isolation, and other authorized employees must be permitted to verify isolation if they choose.

Question 6

Has the employer met the provisions under 1910.147(c)(8) requiring that only the authorized employees who are performing the servicing and maintenance lockout or tagout the energy isolation points?

  • Incorrect. Actually, the employer has not met these provisions.

    Employees, other than the employees performing the servicing and maintenance activity, locked out/tagged out the tank farm's "sour water" valves. In addition, the OSHA investigation revealed that neither the operator of the sour water stripping unit nor the operator of the tank storage farm were trained as authorized employees to perform servicing and maintenance activities.

  • Correct. The employer has not met these provisions.

    Employees, other than the employees performing the servicing and maintenance activity, locked out/tagged out the tank farm's "sour water" valves. In addition, the OSHA investigation revealed that neither the operator of the sour water stripping unit nor the operator of the tank storage farm were trained as authorized employees to perform servicing and maintenance activities.

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