Water hammer accident

A five-person crew was valving in a second stage reheater at an electric power generation station. They were slowly opening two valves to bring the reheater online. Two of the employees were stationed at one valve, and the other three were at the second valve. Two other employees were working in the immediate area, observing the reheater's drain tank levels after having adjusted an automatic valve about 30 minutes before. The drain line for the reheater ruptured downstream of the valves, releasing steam and hot water into the area. The rupture was caused by excessive pressure in the line as a result of a water hammer. The water hammer was caused by the presence of lower pressure on the downstream side of the valves than on the upstream side. This produced a back flow in the line. The operating procedure for the valves in the line during start up operations had been changed earlier in the year to eliminate water hammer that had occurred previously. However, the new changes were not incorporated into the written operating procedures being used at the time of the accident. Seven employees (all five members of the work crew plus the two other employees working in the area) received second-degree burns to multiple parts of their bodies. They were hospitalized for their injuries.

Steam flushing incident

At approximately 9:30 a.m. on January 19, 2005, Employee #1 and Employee #2, were isolating and cleaning a series of three pumps at a refinery in California, while Employee #3 observed the cleaning operation from a distance. The three workers were starting up the refinery's crude unit. They were experiencing screen plugging from crude unit particles inside the crude unit's prefractionator reboiler pump (pump). The screens commonly become plugged during start-up operations. After the charge pump is isolated, workers clean the pump body by injecting pressurized steam into it. Normally the mix of residual crude oil and pressurized steam is removed through a small outlet in the valve body. Employee #1 connected a 40 psi steam line to the top of the pump body. The flexible removable steam line connects to a Chicago fitting on the top of the pump. Just before the explosion, Employee #1 had cracked open the steam line, letting steam into the pump. An uncontrolled pressure event immediately ensued. The overpressurization of the pump body assembly caused the pump suction flange, strainer outlet flange, and flex connector to blow out violently. The spraying hot oil and the fire started by the explosion caused burns to Employees #1, #2, and #3. Employee #1 sustained third and second degree burns over 50 percent of his body and later died. Employee #2 suffered first and second degree burns over his back. Employee #3 suffered first degree burns on his face. Employees #1 and #2 were treated at the Hospital. Employee #3 was treated locally.
Source: OSHA.gov

OSHA's Top 10 Most Frequently Cited Standards FY 2018

OSHA's Top 10 Most Frequently Cited Standards 

(Source: https://www.osha.gov/Top_Ten_Standards.html
for Fiscal Year 2018 (Oct. 1, 2017, to Sept. 30, 2018).

The following is a list of the top 10 most frequently cited standards following inspections of worksites by federal OSHA. OSHA publishes this list to alert employers about these commonly cited standards so they can take steps to find and fix recognized hazards addressed in these and other standards before OSHA shows up. Far too many preventable injuries and illnesses occur in the workplace.

1. Fall protection, construction (29 CFR 1926.501) [related OSHA Safety and Health Topics page]
2. Hazard communication standard, general industry (29 CFR 1910.1200) [related OSHA Safety and Health Topics page]
3. Scaffolding, general requirements, construction (29 CFR 1926.451) [related OSHA Safety and Health Topics page]
4. Respiratory protection, general industry (29 CFR 1910.134) [related OSHA Safety and Health Topics page]
5. Control of hazardous energy (lockout/tagout), general industry (29 CFR 1910.147) [related OSHA Safety and Health Topics page]
6. Ladders, construction (29 CFR 1926.1053) [related OSHA Safety and Health Topics page]
7. Powered industrial trucks, general industry (29 CFR 1910.178) [related OSHA Safety and Health Topics page]
8. Fall Protection–Training Requirements (29 CFR 1926.503) [related OSHA Safety and Health Topics page]
9. Machinery and Machine Guarding, general requirements (29 CFR 1910.212) [related OSHA Safety and Health Topics page]
10. Eye and Face Protection (29 CFR 1926.102) [related OSHA Safety and Health Topics page]

 

An Explosion Protection Strategy | Engineer Live

An Explosion Protection Strategy | Engineer Live

Explosion due to suspended graphite cloud and static electricity

 On September 3 2018, a blast destroyed one of 400 buildings at the RDM plant in South Afirca, which manufactures artillery ammunition.Eight workers were killed.
 As per a report published Herald Live, "Based on extensive testing, assessments and elimination of other initially suspected causes, the most likely cause of the explosion was a build-up of electrostatic electricity in a suspended graphite cloud due to the triboelectric effect, and a subsequent discharge which ignited airborne propellant in the blending drum.”
Read the article in this link

Control of Hazardous Energy by Lock-out and Tag-out

Control of Hazardous Energy by Lock-out and Tag-out: Why Lock-Out and Tag-Out?Lock-out and tag-out (LOTO) is a critical part of a strong all-around safety program. In LOTO, maintenance employees work with production employees to positively prevent all forms of hazardous energy from causing harm. Hazardous e

Hazardous Energy Control Programs : OSH Answers

Hazardous Energy Control Programs : OSH Answers

Loss of containment incident

On September 21, 2003, Employee #1 and several coworkers were working at a chemical plant that deals with nitric oxide. On the day of the accident, a major leak occurred in a stainless steel distillation column. The nitric oxide leaked into the facilities surrounding vacuum jacket and into the atmosphere through a pump, which controls a high quality vacuum inside the jacket to minimize transmission of heat toward the cryogenic distillation columns. A brown cloud quickly formed and the temperature and the pressure inside the distillation column and its surrounding vacuum jacket began to rise. The leak was detected and the vacuum pump was turned off to halt the leakage of nitric oxide into the atmosphere, allowing the pressure inside the column and vacuum jacket to stabilize around 130 psi. Although stabilized, the pressure was far above the normal pressure of less than or equal to atmospheric pressure (14.7 psi). Approximately 3 hours later, an explosion occurred. The operation and process were destroyed, and debris flew through the plant. Employee #1 suffered lacerations due to flying glass and was treated at a local hospital, where he received stitches and then released. A detailed investigation determined that the cause of the explosion was most likely due to something inside the vacuum jacket initiated the dissociation of nitric oxide, a reaction that is very rapid, exothermic, and self-propagating once started.
Source Osha.gov

Lock out, tag out and Try out

At 8:30 a.m. on March 6, 2017, Employee #1 was using an eight foot A-frame fiberglass ladder to remove the steel top cover of the natural gas fuel filtration skid and replace the filters. The employee began to unbolt the steel top cover when it exploded and struck the employee. Employee #1 did not lock out/tag out, nor was the vessel de-energized/purged prior to removing the top cover. The employee sustained blunt force trauma to his body, causing complete amputation of both arms, killing him.
Source:Osha.gov

Are you locking out ALL sources of energy?

On December 28, 2006, Employee #1, a temporary employee, was working as an oil well pumper. He was sent to investigate squeaking belts on well number 11, a Lufkin Pumping unit. Employee #1 did not lockout the pumping unit prior to entering the fenced area, and the counter weight of the pumping unit struck Employee #1 in the head, killing him.
Source Osha.gov

Are you selecting the right sensors?

At approximately 9:40 p.m. on the evening of June 29, 2010, an ignition source in a solvent sludge feed tank ignited flammable solvent vapor. The vapor was in the head space of a partially filled atmospheric tank, either tank Q and/or tank R in the E-II solvent sludge feed tank area. The explosion flame front spread to the adjacent tank, and as a result, both tank covers were removed by the force of the event. The tank cover for tank Q was peeled back to the east but still partially attached. The tank cover for tank R was jettisoned; it struck the E-II processing building to the northwest in several locations before landing on the roof of the Dock 4/5 building to the east. The subsequent tank fires resulting from the explosion were extinguished by the local fire department. The likely ignition source was determined to be ultrasonic high-level sensors within the solvent sludge feed tanks. Apparently they had separated due to solvent degradation, exposing internal wiring. There were no injuries or fatalities.

Do not enter confined spaces without a proper permit even for a short time!

On May 5, 2018, Employee #1 was retrieving a plastic liner bag from a chemical container that had fallen into Reactor CP-2; a confined space. The permitting process, including air monitoring and setting up of ventilation, had not been conducted. As Employee #1 descended a ladder to access the reactor, he passed out at the first rung and fell to the bottom of the reactor. A coworker, who witnessed Employee#1 enter the space, contacted the control room to notify them of the incident. Emergency services were contacted and, upon arrival, recovered Employee #1 from the reactor. Employee #1 was determined dead. Air monitoring conducted by emergency services, following the incident, showed an oxygen concentration of eleven percent.
Source: OSHA.gov

Do you issue confined space entry permit for tankers?

Employee #1 was power washing the outside of the semi-truck tanker trailer. The employee entered the tanker trailer to wash the inside and was not found for two hours. The fire department was called to rescue the employee. Atmospheric monitoring found atmospheric levels of hydrogen sulfide at 100 ppm and hydrogen cyanide at 30 ppm. No written evidence of atmospheric monitoring was available following the employee's recovery from the space, and no ventilation of the space prior to or during the entry was performed. No attendant or entry supervisor was assigned to the entry. Employee #1's death was determined to be chemical asphyxia by vitiated atmosphere with hydrogen sulfide and hydrogen cyanide gasses.
Source: www.osha.gov

Accident due to hazardous energy

At 11:38 a.m. on March 6, 2018, an employee was using an electric impact gun to tighten the bolts connecting a 12 Inch diameter pipe flange and the end cap in place. As the employee stood over the vertical pipe tightening the bolts, a connection below ground failed. This failure sent the pressurized pipe upwards and caused the impact gun to strike the employee in his chest. The employee was killed.

Source Osha.gov

Dangers of pneumatic testing

On July 14, 2009, Employees #1 and #2 were performing a pneumatic test to verify leak tightness of a new meter station at the Midcontinent Express Pipeline. The test medium was nitrogen gas, and the system being tested included piping and two pressure vessels. Numerous leaks were found in the system during the test. The system reached the required test pressure of 2225 psig at approximately 3:25 p.m., and Employee #1 observed that the pressure on the system had dropped to 2205 by approximately 3:30p.m. Employee #1 was then replaced at the test table by Employee #2. As Employee #1 walked away from the test table, the door on the PECO separator (a pressure vessel) blew off, releasing pressurized nitrogen gas that sent projectiles flying. Employee #2 was killed, and Employee #1 suffered burns and was hospitalized.

Source: Osha.gov

Pressure testing fatality

On March 4, 2005, Employee #1 (leadman) was performing a hydrostatic pressure test on a large stainless steel pressure vessel at a plant which manufactures pressure vessels. The tank was cylindrical, about 14 in. diameter and 24 in. long. The tank was pressurized to 150 psi for the test. Upon successful completion of the test, he was draining the water from the tank. He soon discovered that the water would not drain very quickly, as the internal configuration of the tank was such that a vacuum was being created here were inadequate air openings to displace the draining water. After consultation with the plant supervisor and plant manager, it was decided that compressed air would be pumped into the tank to force the water out for a short time, then more openings would be exposed and the water could drain by itself. 110 psi air was pumped into the tank by Employee #1 and supervisor, and the water began draining. The supervisor turned the job back to Employee #1. Sometime later, the air hose was disconnected, and the compressed air was also allowed to bleed off. About an hour after the draining began, Employee #1 ordered another coworker to close the drain valve. Employee #1 then went to the area of the drain valve and is presumed to have begun to remove the quick-closure clamps used to seal a tank portal several inches higher than the drain. Normally, the water would be pumped from an opening near, but above the drain when the water levels had dropped to near the drain level. This employee apparently had seen air bubbling out in the drain line and assumed (correctly) that the water level had dropped to near the drain level. 

 The air pressure, however, had not completely off, and when the clamp was loosened, it flew off at him accompanied by a massive air pressure release. Employee #1 received head and neck injuries when being struck by the blanking plate and when his head was snapped back from the release. Employee #1 was paralyzed in the hospital for several days before he died of respiratory and other complications. The employee and the supervisor were very experienced at hydrostatic pressure testing, but pneumatic pressure testing was extremely rare at the plant. They had never had to pump in air to drain a tank before. The company had procedures for both hydrostatic and pneumatic tests, and each employee was trained several years earlier on these procedures. Several days earlier, an attempt to fill the tank with water for the test was unsuccessful, as the same lack of tank openings near the top of the tank would not allow for this to be filled. An extra hole was drilled to allow for filling. Quick-closure clamps are very rarely used during these tests, but the type of clamp used for the test is dependent on the type of clamp that will be used once the tank is put into production. A witness said that the employee was hurried during the draining process. It was Friday, and the tank needed to be shipped on Monday, and there was more work to be done on the tank. He was also working on another tank nearby. The tank had two pressure gauges mounted at the high point of the tank, these both should have read water and air pressure as well. Both were working before and after the test. The gauges were on the same line as was used to force compressed air into the tank. To read these gauges, the worker would have to walk to the end of the tank away from the drain and climb up a shortstepladder. There was no procedure or training for doing the work in this particular manner. How long to pump in the air, what steps were needed to ensure that the pressure was dissipated, what measures were needed to avoid reintroduction of pressure or how safely release the pressure was not specified? The normal hydrostatic test calls for the employee to make sure that the pressure is at zero before opening the tank. In a normal hydrostatic test, the tank pressure would drop to zero very shortly after the tank draining began. 

Source: Osha.gov