Thresher Sinking Atlantic Ocean - Essay Example

? Sinking of the Thresher in the Atlantic Ocean in 1963 Table of Contents 2 Introduction 3 Background to the Thresher Disaster 3 Investigations into the Sinking of the Thresher 5 Findings and Recommendations 5 Impact on Engineering Practice 9 Conclusion 11 References 12 Abstract The US submarine, Thresher, sunk in 1963. The submarine which had been built to be a leader in the industry met its fate while undergoing trials in the deep sea with 129 individuals onboard. Investigations into the disaster reveal that the accident could have been caused by a failure of a salt water pipe. The disaster is also blamed on an electrical fault that saw vital pumps stop working. Known to be the worst submarine accident in U.S. history, engineers have learnt a lot from the event. Engineers have learnt the importance of upholding standards and procedures, testing procured materials, and prioritizing safety over other factors when it comes to designing and building products. Sinking of the Thresher in the Atlantic Ocean in 1963 Introduction Engineers are credited for designing different machines, equipment and structures that serve to overcome certain specific problems. As they undertake their works, engineers go to great depths to ensure that whatever they design work as efficiently as possible. Understanding the risks that their designs may pose to the public and infrastructure, they often do a lot of calculations and incorporate safety measures wherever they can in their designs. Furthermore, they are tasked with choosing materials that have properties that match the functions for which they are to be used. In as much as engineers do their best to ensure that what they design and make work without failing, this is not always the case. Sometimes, engineering systems fail leading to massive losses. One case of failure that resulted from an engineering error is the sinking of Thresher submarine in the Atlantic Ocean. This paper will explore the events leading to the sinking of the submarine before presenting the lessons engineers have learnt from the disaster. For its wondrous design and capabilities, the Thresher became the U.S. Navy’s lead vessel for a couple of years before it met its fate at sea. Background to the Thresher Disaster The USS Thresher (SSN-593), a submarine designed to be powered using nuclear energy, was built by the U.S. Navy at the Portsmouth Naval Shipyard (Bentley, 1975). The submarine, which was at its time, the most advanced, was engaged in several sea trials in the Caribbean sea and the Atlantic Ocean between 1961 and 1962 only to prove its prowess as a war machine. The machine was so technologically advanced that it was rated the fastest and quietest submarine ever to be built in the world then, specifically dedicated to searching and destroying Soviet submarines (Bentley, 1975). Its sonar system had the capacity to detect ships and other submarines as far away as other submarines could not detect. Furthermore, it was installed with a highly technical weapons system which included the newest anti-submarine missile that the U.S. Navy had – the SUBROC. Apart from these amazing characteristics, the Thresher could dive far below any other machine of its ilk. Having been hit by a tug that damaged its ballast tanks while moored at Port Canaveral, Florida, it was necessary for the Thresher to undergo repairs, have its systems examined and before it could be fully certified for use during operations. After the submarine was finally certified to be operational, it was set to undergo routine tests on April, 9, 1963 (Bentley, 1975). Under the command of Lieutenant Commander John Wesley Harvey, the ship left the Portsmouth Naval Shipyard in Maine in the company of a rescue ship, Skylark, at 8 am. The rescue vessel accompanied the Thresher so that it could provide rescue services to those onboard the submarine in case of any problem. The Skylark had the capacity to provide rescue services to the submarine up to a maximum depth of about 850 feet (Bentley, 1975). The submarine engaged in a couple of diving trials on the fateful day, which it accomplished without experiencing major problems. The trials included a test dive to half the submarines design test depth (750 feet) Satisfied that it was safe to conduct more trials in deep water, the two vessels headed deeper inside the ocean (Polmar, 1964). On April 10, 1963, the submarine undertook a routine test dive that would see it go 1,300 feet below the water surface (history.com, 2013; The Boston Globe, 2013; National Geographic, 2013). The submarine dived deeper in the water travelling slowly and in circles below the Skylark. The two vessels maintained communication using a UQC (an underwater radio) as the submarine moved deeper and deeper below the surface Polmar, N. (1964). At every additional 100 feet, the submarine’s crew stopped and checked how its systems functioned. Almost reaching the test depth, the Skylark received a couple of garbled messages from the Thresher’s crew. Thereafter, Skylark received no further communication from the submarine. A lot of effort was implied in an attempt to find and rescue the occupants of the submarine which went missing. Days later, the remains of the submarine were found about 8400 feet below the sea level. In what is today recognised as the worst submarine disaster in U.S. history, a total of 129 lives were lost (history.com, 2013). Investigations into the Sinking of the Thresher Soon after the submarine was declared missing, several expeditions were conducted to find its remains and piece together possible causes of the disaster. Major sections of the submarine were photographed and video taped, including the stern plates, bow section, sail, and engineering space section. Given the magnitude of loss that had been witnessed with the destruction of the Thresher, the U.S. Navy constituted a court of inquiry in Kittery, Maine to investigate the incident. The court listened to several witnesses, examined exhibits and documents before coming up with a conclusion on the probable cause of the disaster. While the court finally presented its verdict in regard to the matter, subsequent investigations have been conducted with a focus on the detections of SOSUS to present a different conclusion. In this respect, Bruce Rule conducted an investigation and concluded that the accident was a result of an electrical fault. Findings and Recommendations According to the court, the most probable cause of the disaster was a failure in the piping system of the submarine. The court noted that one of the saltwater system pipes located in the engine room must have ruptured leading to electrical faults that caused the vessel to lose power (Burgeson, 2013; National Geographic, 2013). According to Adm. Kirkland Donald, the Thresher accident could most probably have been caused by the failure of a silver-braze joint as the submarine ventured close to its test depth. The pressure caused by a spray of sea water could have caused the shorting of the submarine’s electrical equipment that led the nuclear reactor to shut down. Tests using ultrasound machines had earlier detected problems with roughly 14 percent of the brazen joints that had been tested. These joints however were noted not to pose a significant threat to the submarine. It was also established through simulation that the inability to blow the ballast tanks was due to frozen water blocking the flask’s flowpaths as air at high pressure exited through valves. The Thresher accident was also attributed to the slow speed at which the nuclear reactor system was designed to restart after a stop. It would have taken close to ten minutes to have the reactor restarted after being stopped – a long period that would easily allow a lot of damage to occur in the vessel under normal circumstances. According to Adm. H.G. Rickover, the then head of the nuclear propulsion program in the Navy, very little is known of what really was happening in the Thresher when it met its fate at sea (Bruce & Polmar, 2013). In this respect, Rickover tends to differ with the conclusion by the court that the pipe failure caused the disaster. Rickover noted that the submarine’s coolant pumps had been detected by the seafloor sound surveillance system (SOSUS) installed by the Navy (Bruce & Polmar, 2013; Rockwell, 2002). At the time of this detection, the vessel was approaching about 1000 feet in depth. A few minutes after the detection of the pumps in action, SOSUS also detected that the electrical bus that was serving non-vital elements of the submarine had failed. The system further detected that the reactors were operating normally so that the submarine was being propelled as required. Rickover argued that with the failure of the electric bus, the main coolant pumps stopped working and the reactor shut down. Rickover’s argument is based on the premise that when the Skylark received the message “minor difficulty” followed by a gabbled message, the submarine was trying to blow ballast so that she would rise to the surface (Sharp, 2013; Bruce & Polmar, 2013). This effectively indicated that the vessel had lost propulsion. Because the submarine was not able to rise to the surface as a result of ice formation in the ballast system as confirmed by simulation, it sank to its collapse depth without being flooded (Bruce & Polmar, 2013). The Skylark received a message from the Thresher at 9.17am containing the number 900. It is believed that the number was given in reference to the test depth. In this regard, it is argued that the submarine crew were trying to indicate that the vessel had surpassed its test depth by 900 feet and was about 2,200 feet below the water surface (Bruce & Polmar, 2013). Lieutenant James Watson one of the naval officers manning the Skylark noted that he soon afterwards heard a sound like that of a ship breaking up over the UQC. Henceforth, the thresher gave no response to the calls by Skylark’s crew. Records indicate that SOSUS detected extremely high amplitude events at around 9.18 am. These events are estimated to have occurred as far as 1,300 nautical miles away (Bruce & Polmar, 2013). Based on the characteristics of the events as detected by SOSUS, it is argued that the pressure hull of the submarine collapsed at a depth or roughly 2,400 feet - over 400 feet below the predicted collapse depth of the vessel (Bruce & Polmar, 2013). What this means is that its pressure hull and salt water piping systems had worked well beyond their design specifications. An analysis of SOSUS detection system revealed that the pressure hull as well as the internal compartments of the vessel were destroyed in about 10 milliseconds - a time so short that the event could not be detected by the perceptions of those onboard the vessel (Bruce & Polmar, 2013). Based on measurements made during the sinking of starlet submarine in 1969, it has been concluded that the water-ram that resulted when the Thresher’s pressure hull was breached reached a velocity of roughly 2,600 miles per hour (Bruce & Polmar, 2013). The force of the water-ran was so high that it would have easily ripped off the pressure hull as confirmed by photographs taken of the remains of the vessel. A number of mistakes led to the sinking of the Thresher according to Navsource (2013). One of the mistakes that the Navy made was choosing to test the vessel in extremely deep waters. While the vessel had a test depth of 1,300 feet, the location chosen for the test was actually 8400 feet as noted by Navsource (2013). Secondly, the accident was blamed on substandard brazing that could have led to failing of the salt water pipe. While there were several standards and procedures that should have been followed during the overhaul of the Thresher, experts note that these were not, followed (Arlington Cemetery 2013). The engineers in charge of overhauling the machine focused on abiding by the standards set for the nuclear power plant and gave less attention to the rest of the submarine. More particularly, they ignored important systems such as the steam and salt water systems which were equally important for the safety of the vessel during operation (Arlington Cemetery 2013). While it was required that closely fitting parts be welded and then brazen to ensure that the joints created were water tight, the engineers used hand held torches to heat many crucial albeit less accessible pipe joints. This meant that the joints so created were weak and could not readily withstand the high pressures they were subjected to when the submarine was in operation. While the engineers were required to abide by new quality assurance standards that involved non-destructive testing of materials, this was not done (Arlington Cemetery 2013). Instead, the engineers opted to use the traditional method of testing silver-brazed joints and ignored the recommended ultrasonic testing program which they considered burdensome and time consuming. Another failure on the part of the naval officers was with respect to the procurement of materials. The naval officers went against government specifications and procured substandard materials such as valves which could have caused the disaster to occur (Arlington Cemetery 2013). The disaster was blamed on electrical bus failure that led to the coolant pumps stopping. According to Admiral Hyman Rickover, the loss of the Thresher should not be blamed on a specific component, system, person, weld or braze but rather on the design philosophy, construction and inspection of the U.S. navy’s shipbuilding program (Bentley, 1975). Rickover recommended that the Navy re-evaluate its practices and ensure that even as it pursues innovative advancements, it should not be throw good engineering principles to the wind. The Court of Inquiry, on the other hand, recommended that the U.S. Navy institute a program of design that is more rigorous and that features safety inspections during the production of naval vessels and systems (Bentley, 1975). Following this recommendation, the U.S. Navy instituted the SUBSAFE program which has seen a drastic reduction in the number of submarines lost without being engaged in combat (Navsource, 2013). Ever since the Thresher was lost, the U.S. has taken measures to ensure that its nuclear powered submarines can have their reactors restart rapidly in case they stop functioning for any reason. Impact on Engineering Practice Engineering disasters have often seen engineers make significant changes in the way they do things or in their designs. With the loss of the thresher, the U.S. Navy instituted a raft of measures that have ensured their vessels and systems are designed with safety taken into consideration. In fact, many of the Navy’s vessels and systems are designed with fail safe mechanisms. In the words of Vice Admiral Bruce Demars, the Thesher disaster has seen the Navy change its design, construction, inspections, tests, safety checks, and other of its processes (history.com, 2013, par. 6). Learning from the disaster, submarines are today installed with High Pressure Air Compressors (HIPACS) that serve to remove water that is known to freeze the main emergency tank blow valves when the emergency system is most needed (Navsource, 2013). While previously submarines were routinely subjected to a gauntlet of depth charges, this is no longer the case with operational vessels according to Navsource (2013). This procedure was done to inflict structural damages to submarines. These damages would be measured and evaluated. Furthermore, nuclear powered submarines are today designed to have fast scram recovery systems. The system works such that when the nuclear reactor stops functioning, it is quickly restarted to ensure that the submarine does not remain without power for long (Navsource, 2013). Before the Thresher disaster, equipment in the submarine were cooled using sea water that passed through a system of pipes (Navsource, 2013). This meant that the submarine had several feet of pipes that carried water at high pressure. Instead of such pipes, submarines are today installed with large heat exchangers that transfer heat from the vessel’s systems to the sea water at much lower pressures. Instead of the water rotating within the submarines system in a closed circuit as was previously the case, the heat exchangers work such that fresh sea water is used to cool the vessel’s systems (Navsource, 2013). Yet another change that has been instituted with respect to submarines is the application of welds, brazing and radiography. Before the Thresher disaster, pipes were cut, welded and sealed using braze as noted by (Navsource, 2013). Brazing was done to ensure that water did not pass through the welds. However, getting a perfect weld using silver was difficult to achieve. Furthermore, the welds that were made on the pipes were not strong enough to withstand the high pressures that they were constantly subjected to. Today, welding and brazing are not commonly done on pipes used in submarines (Navsource, 2013). Yet again, it was not common practice to check welds on submarine parts using radiographic equipment. This meant that having welds that were substandard was not uncommon on submarines. Following the Thresher incident, radiographic pictures of critical welds are taken whenever submarines are being made or when they are undergoing service. Communication between different individuals, vessels, and command bases is important for the effectiveness of members of the Navy. The Thresher was installed with a radio system that was quite unreliable especially at great depths. Because of this, it has been difficult to establish with certainty the exact root cause of the Thresher disaster. Submarine vessels are nowadays installed with more reliable high-tech communication equipment. The engineering field as a whole has learnt from the Thresher disaster. Engineers have learnt that engineering, construction and design must be given equal focus when dealing with nuclear systems and systems that do not apply nuclear energy so long as they impact on the integrity and safety of the product (Arlington Cemetery 2013). Yet again, engineers have come to learn that when selecting standards for the performance of tasks, safety and effectiveness should override such factors as time and resource constraints. Furthermore, engineers have learnt that it is important for management to communicate near miss events to different players as it contributes toward resolving problems and preventing bad events in the future (Arlington Cemetery 2013). In the production of products, engineers rely on materials. From the Thresher event, engineers have learnt that whenever they procure materials, it is important for them to check their quality under working conditions to verify how suitable they are for use. There are chances, for example, that vital parts are assembled using counterfeit parts which may easily fail under working conditions. Conclusion The loss of the Thresher remains a big blow to the United States of America to-date. The vessel which was designed to reach depths of up to 1300 feet below the water surface was a great innovation by the U.S. navy. The submarine was so technologically advanced that it had no match at the time of its destruction. The vessel was also faster in speed, more stealthy, and was installed with high-tech weapons and detection systems to enable it search and destroy enemy submarines. Various hypothesis have been postulated regarding the destruction of the submarine. While the court instituted by the navy concluded that the Thresher met its fate as a consequence of a failure in the piping system that eventually resulted in the loss of power, some experts think otherwise. Bruce Rule, based on an analysis of the signals detected by SOSUS hypothesised that an electrical fault that led to the stopping of the coolant pumps was the root cause of the accident. With the loss of power, a clogged ballast system, and inability to de-ballast, the vessel sank below its predicted collapse depth leading to the implosion of the pressure hull. Following the loss of the Thresher, several changes have been made in the U.S. Navy to ensure that similar accidents do not occur. One of the main changes in this respect is the SUBSAFE introduction of the program. The Navy has also seen changes made in the way pipes are joined for submarine use. Engineers have learnt a lot from the loss of the Thresher. For one, they have learnt the importance of testing materials that they procure. Secondly, they have learnt the importance of abiding by standards and procedures. Furthermore, they have learnt that it is important to assign equal focus to all systems that impact on the safety and effectiveness of the system as opposed to one such system alone. References Arlington Cemetery (2013). USS Thresher (SSN-593), 1961-1963. Retrieved November 30, 2013 from http://arlingtoncemetery.net/uss-thresher.htm Bentley, J. (1975). The Thresher Disaster, New York: Doubleday. Bentley, J. (1975). The Thresher disaster; the most tragic dive in submarine history. Garden City, N.Y: Doubleday. Bruce, R. & Polmar, N. (2013) 50 years later, a look at what really sank the Thresher. Retrieved November 30, 2013 from http://www.navytimes.com/article/20130404/NEWS/304040021/ Burgeson, J. (2013). Thresher sinking remembered a half-century later. Retrieved November 30, 2013 from http://www.ctpost.com/local/article/Thresher-sinking-remembered-a-half-century-later-4415345.php history.com (2013). Atomic submarine sinks in Atlantic. Retrieved November 30, 2013 from http://www.history.com/this-day-in-history/atomic-submarine-sinks-in-atlantic National Geographic (2013).Thresher: Going Quietly, National Geographic. Retrieved November 30, 2013 from http://www.nationalgeographic.com/k19/disasters_detail2.html Navsource (2013). Thresher (SSN-593) Loss & Inquiry. Retrieved November 30, 2013 from http://www.navsource.org/archives/08/08593b.htm Polmar, N. (1964). Death of the Thresher. Philadelphia: Chilton Books. Rockwell, T. (2002). The Rickover Effect : How One Man made a Difference. Lincoln: IUniverse. Sharp, D. (2013). Deadliest Submarine Disaster In U.S. History Remembered 50 Year Later. Retrieved November 30, 2013 from http://www.huffingtonpost.com/2013/04/05/uss-thresher_n_3020543.html The Boston Globe (2013). Sinking of sub Thresher still wounds, 50 years. The Boston Globe. Retrieved November 30, 2013 from http://www.bostonglobe.com/metro/2013/04/06/fifty-years-later-uss-thresher-loss-remembered-years-later-honoring-lost-sub-thresher/K54KR5EU0DL7YLYt9nm13I/story.html Read More