Investigation #99TX46701

An Operations Manager for a Well Servicing Company in Texas, Died When a Length of Pipe Mounted on Top of a Skid-mounted Mud Pump Broke Loose and Struck Him in the Head


On October 29, 1998, a 63 year-old male operations manager (the victim) died when a length of pipe mounted on top of a skid-mounted mud pump broke loose and struck him in the head. The work crew was in the process of sealing a well. They had finished pumping in cement and were starting to pump in water to displace the cement down to 10,000 feet. As the operations manager leaned over and looked into one of the two mud mixing tanks, he was struck on the side of the head by a length of pipe (return line) from the pump that had not been secured.

The TX FACE investigator concluded that to reduce the likelihood of similar occurrences, employers should:



On October 28, 1998, a 63 year-old male operations manager (the victim) died when a length of pipe mounted on top of a skid-mounted mud pump broke loose and struck him in the head. The TX FACE program officer was made aware of the incident by the regional OSHA office on December 17, 1998. A visit to another site by the TX FACE program officer, where the mud pump had been relocated, was made on February 17, 1999. The new operations manager and the mud pump operator were interviewed. Pictures were taken of the mud pump. An autopsy report was obtained.

The employer was a well servicing company. The company employed 50 workers, two of whom performed the same duties as the victim. The employer had been in business for 32 years. There were six other workers at the site at the time, however, no one witnessed the event. The mud pump operator was standing next to the victim but had his back to him.

The employer's safety program was managed by the operations manager. A written safety program was in place but there were no written work procedures specific to the victim's task. Safety meetings were conducted on a monthly basis. Tool pushers would also conduct daily job site talks on what was to be done that day along with any safety related issues. The company hired experienced workers so new hire and/or refresher training was not conducted.

The victim had been employed with the company for eight years. He had 26 years experience in well servicing which included cementing wells.

The company conducted pre-employment physicals and drug screening. This was the first fatality experienced by the employer.



A work crew for the employer was in the process of sealing a well. They were performing an operation referred to as "squeezing off perforations" or "squeezing". It involved pumping cement into the hole and then pumping in water to displace the cement further down into the well formation. They were displacing the cement down to a depth of 10,000 feet.

A tri-plex, skid-mounted mud pump was used for this operation. The mud pump was equipped with two mixing tanks. Piping ran across the top of the two tanks which included two discharge lines and two return lines. Pipes were normally secured with u-clamps. In this incident, one return line had not been properly secured.

The work crew first pumped water into the annulus, which is the area surrounding the casing in a well. Cement, with a retarder mixed in to prevent the cement from hardening too soon, was then pumped into the well. The mud pump operator pumped in a total of 15 barrels of cement. After pumping in the cement, the mud pump operator started to pump in water in order to displace the cement down to a depth of 10,000 feet.

The victim was assisting the mud pump operator by looking into the mixing tanks. He was observing the "notches" on the inside of the tank which indicate how much water had been pumped into the well. The mud pump operator was pumping at 1,400 psi. He did not observe any abnormal fluctuations of pressure. The mud pump piping was rated at 5,000 psi. The relief valve was set at 4,000 psi.

After about 20 barrels of water were pumped, the mud pump operator heard a loud noise. The victim, who had been leaning over and looking into one of the mixing tanks, was struck on the upper left side of the head by the return line which had not been secured. Excessive pressure caused the return line to flip up and the ball valve to blow off the end of the return line. The excessive pressure was instantaneous and caused the relief valve mechanism to fail. The ball valve was never found.

Emergency Medical Services (EMS), Sheriff, and the Justice of the Peace were notified and they responded to the scene. The Justice of the Peace pronounced the victim dead at the scene.



(Note: the report hasn't arrived yet.)



Recommendation #1 - Employers should ensure all piping (discharge and return lines) that are mounted on top of mud pump tanks are secured.

Discussion: The pipes mounted on top of the mud pump were connected together by "T" and 90 degree "elbow" connections. Where the pipe is screwed into one of these connections is the point excessive pressure can cause the "T" or 90 degree "elbow" to rotate. Securing the pipes to the tank would prevent this from occurring if an excessive amount of pressure builds up.

Employers can refer to the American Petroleum Institute RP54-1981, Recommended Practices for Occupational Safety and Health for Oil and Gas Well Drilling and Servicing Operations, para 8.14.3, and ANSI/ASME Standard B31.1e - 1979 para 122.6 for additional information.


Recommendation #2 - Employers should develop a checklist for mud pump operators and supervisors to ensure that all the steps necessary to conduct a cementing operation have been performed.

Discussion: In this incident, the source of the excessive pressure could not be determined. Workers can protect themselves from this type of hazard by ensuring equipment is properly installed up. In this incident the pipe that struck the victim was not secured. Also the ball valve that was blown off the end of the pipe may have been closed. It was never found.

Using a checklist can guide workers through a process that ensures all necessary tasks are completed and equipment is in the correct configuration.


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