Dry gas seals 101 presentation free download as powerpoint presentation. Analysis of historical dry gas seal failure data asme digital. Outboard of the dry gas seal is a barrier seal, which separates the gas seal from the compressor shaft bearings fig. Today, converting to dry gas seal technology is an industry best practice. Seal environment solutions from experience has proven that process contamination is the biggest single contributor to premature gas seal failure maintain optimum seal condition increase compressor availability prevent liquid contamination at seal faces prevent process debris contamination increase dry gas seal mtbf nace material compatibility. Dry gas seal systems for centrifugal compressors page 4. Remedies for seal failure root cause failure analysis. John crane reports that such a deficiency causes a majority of the seal failures the company sees during compressor. Dry gas seal systems for centrifugal compressors page 3 of. The finding showed that approximately 80 percent of compressor failures were due to seal oil system faults. Key considerations for dry gas seal performance flow.
Skipping initial startup procedures and installation errors are a big factor when it comes to mechanical seal failure. The seal gas used as the sealing medium is usually a clean, dry and cool gas that is compatible with the process gas being compressed. Open root cause failure analysis seal gas filter dp transmitters calibration seal gas filter maintenance calibrated during 8k ppm found dirty with black carbon dirt soot. Feel free to contact us regarding your bad actors and a proposal for our services. This compressor adopts tandem structure with intermediate labyrinth seal as its dry gas seal type. A booster package provides a small amount of gas flow when the. Centrifugal compressor wet seals seal oil degassing and control. There are significant advantages to convert to dry gas seals, even though oiltype seals can still function properly at times. After a dry gas seal failure, the seal should be sent to the seal manufacturers facility for dismantling and investigation. Inadequate fuel gas pressure during start up typical conditions on inboardoutboard seal will include running. The alarm and shutdown devices of the seal oil system must be of reasonable range and sensitivity and. Poor buffer gas fluid main cause of gas compressor seal. The compressor dry gas seal has officially been put into operation for six months, it damaged twice and caused the device to unplanned shutdown, seriously affected the long term operation.
The gas seal housing, including seal facessurfaces, andor bushing. Mar 29, 2018 facility operators in the oil and gas industry have raised concerns on how to solve their top failure modes. Seal was started on shaft, then removed and reinstalled. The benefits of using dry gas seals to pump liquids pumps. Aug 02, 2017 a barrier seal should be suitable for bidirectional rotation.
Overview as mentioned numerous times throughout this book, the running gap between the primary and mating gas seal rings is only a few microns, approximately 120th the diameter of a human hair. Field applications of dry gas seal designs were completed in 1952. As the seals gain in popularity know their advantages and disadvantages. There are literally hundreds of variables that can affect the life of your seal. Aug 02, 2017 a dry gas seal control system must have an adequate range and controllability to maintain a minimum 16 fps 4. The finalized technical program will be posted this summer. Based on experience, heavy contacts between seal faces have been observed in many failed seals. Based on experience, heavy contacts between seal faces have been observed in.
A mechanical seal will normally be a component part of. Sealing failure analysis a seal is like a book itll tell you a story. Wet seal degassing recovery system for centrifugal. The outboard labyrinth reduces warm seal gas leakage to the process side. Aura is the next generation of john crane gas seals that ensure reliability and uptime in missioncritical applications. Key considerations for dry gas seal performance flow control. Static pressure testing for mechanical wet seals, not limited to but including api 682 test requirements. Failure analysis is a multifaceted, holistic approach to determine how and why a material or product failed. We will diagnose the reason for premature seal failure and provide corrective actions to prevent it from happening again. Analysis of historical dry gas seal failure data request pdf. An unused seal might develop a dry spot susceptible to weathering and cracking. Wet seal degassing recovery system for centrifugal compressors 2014 2 one partner has reduced methane emissions from centrifugal compressor seal oil degassing by separating gas from seal oil in a small separatordisengagement vessel and routing it back into the compressor suction, to high pressure turbine fuel gas, or to low pressure fuel. Dry gas seals 101 presentation gas compressor bearing. The seal gas supply pressure must be a higher pressure than the compressor seals will ever encounter.
Pump solves dry run failures in oil and gas markets parker. Contamination is one of the leading causes of dry gas seal failure. Compressor was stopped and performed static test with low pressure nitrogen to confirm the nde seal health condition before change out as the last dry gas seal was changed one year back due to the same problem. Dry gas seals are now accepted world wide as a mature product handling gases on a very wide variation of plants and compressors. Therefore, in hightemperature sco 2 turbines, the seal buffer gas also serves to cool the seal. Exposure to the dirty gases will make the dry gas seal groove ineffective causing the damage to the seal faces. He serves on the api692 committee for dry gas seals and systems.
A leading oil company has found a higher rate of failure on medium and high pressure dry. The best way of using the handbook and estimating the failure rate of a mechanical seal is use of the failure mode, effects and criticality analysis fmeca. The information found in dry gas seals handbook will help you make informed decisions regarding the application, operation, and maintenance of dry gas seals. The seal gas supply pressure must be a higher pressure than. Mtbr for dry gas seals mechanical seal engineering eng.
Once this is established and the gas panel is suitably designed to provide continious dry clean gas these seals can run for many years trouble free. Flowserve has extensive experience in dry gas seal retrofits including many of the worlds first retrofit applications. Hence the proper design and monitoring of dry gas seals are most important. Apr 15, 2008 temperatures could fall below the dew point of the seal gas then the seal gas lines must be heat traced. Analysis of historical dry gas seal failure data turbo expo. Lube oil transient issue, dry gas seal system issues, performance issues, steam turbine failures. A practical datadriven analysis case studies for gas turbine operators investigation and solution to steam turbine governor valve repetitive failure thermal gradient due low suction temperature causing swashing in dry gas seal. Seal materials and selection brief overview seal families api flush plans use of seal selection guide practical exercise with worked examples handson fitting metal bellows seal why seals fail overview seal failure analysis aids dry gas seal design and operating principles outline of the operation of a. Because of this, most dry gas seals have a maximum operating temperature of 177c. The benefits of using dry gas seals to pump liquids. Dry gas seals may or may not provide positive gas sealing if the seal faces are damaged or distorted. Gas up your sealing knowledge as users become more familiar with gas seal technology and its advantages, gas seals are being applied to a wider variety of applications and equipment than ever before. Dry gas seal contamination lessons from the field on globalspec. Another type of dry gas seal failure is due to misalignment.
In total, eight companies contributed 194 failures. Jul 22, 20 the gas seal housing, including seal facessurfaces, andor bushing. Secondary seal failure can be caused by oil contamination from the adjacent bearing, and is not. Case study on investigation and resolution of dry gas. Dry gas seal assemblies are available in single, doubleopposed, and tandem configurations to suit all applications. With more than 19 years of experience in the dry gas seal industry, johnson leads the technical sales of eagleburgmanns dry gas seal and systems business.
Other services include rotor dynamic and gas phase analysis. Poor buffer gas fluid main cause of gas compressor seal failure. Condition reporting and seal failure analysis to provide evidence of potential process or equipment problems to improve seal life. Complete failure can occur in destructive scenarios like severe surge, but can also occur if the outer secondary seal has failed but the failure has not been detected. These advantages include very low gas leakages and losses, and an overall simpler system than a conventional oil system. Analysis of historical dry gas seal failures data in natural gas compressors. The nde primary vent high pressure indicated the high leakage of the dry gas seal. The turboexpander dry gas seal consists of the conventional dry gas seal mating ring and primary ring, an outboard labyrinth, an inboard labyrinth, and the cavity to be vented, if desired. Complete compressor drygas seal failure gas compression. Scribd is the worlds largest social reading and publishing site. It has a lot of applications in natural gas and chemicals industry, it can be found in gas compressors and gas turbines as it has high operating stability and low maintenance cost 1. Field services include installation, commissioning, troubleshooting and failure analysis.
Performed dew point analysis for the current gas composition and identified the required seal gas temperature. Dry gas elastomer bellows metal bellows noncontacting oring pusher ptfe bellows ptfe wedge slurry split vessel and agitator gas seal systems wet seal systems equipment alignment api general process industries turbomachinery filtration systems fcf seal gas filtration fuel gas filtration fuel oil filtration liquid filtration seal gas filtration. Dry gas seal dgs is considered one of noncontacting dynamic seal, which used for sealing leakage around rotating machines shafts. The database includes details on dry gas seal and separation seal configuration, seal gas supply, operating history, conditions at time of failure, and failure symptoms, including any results from failure analyses performed by the survey respondent. Common dry gas seal failures are discussed below along with their causes and remedies.
Sometimes the seal will swell and reseal after some period of reuse, while on other occasions the leak will gradually get worse as the seal disintegrates. Dry gas seal systems for centrifugal compressors page 4 of. All dry gas seals need additional protection from the process and the bearing lubrication sides of the seal history. Apr 27, 2011 common dry gas seal failures are discussed below along with their causes and remedies. This gas is not suitable for sale and is either released to the atmosphere, flared, or routed back to a process.
Please note that the manuscript showcase does not reflect the final tps program, and is subject to change. Detailed information is required to make a failure analysis of a damaged shaft seal and subsequently prevent new failures. Pdf improving dry gas seal reliability researchgate. Recycle hydrogen compressor group is the core equipment of heavy coker gas oil hydrotreater unit of refinery. A dry gas seal control system must have an adequate range and controllability to maintain a minimum 16 fps 4. The dry gas seal contains temperaturelimited static seals between the seal cartridge and the casing and between the shaft sleeve and shaft. Inboard of the dry gas seal is an inner labyrinth seal, which separates the process gas from the gas seal. Failure to consider specific plant operating conditions and seal system lessons learned has resulted in dry gas seal systems of low mtbf less than 12 months and large revenue losses. Avoid unplanned shutdown and concurrent high repair costs. Failure analysis is a critical aspect of product development and system improvement which not only helps us learn from the past, but helps prevent future failures.
Inadequate fuel gas pressure during start up typical conditions on inboardoutboard seal will include. Problems at the faces carbons, ceramic, silicon and tungsten carbide faces wear heat hangup. Vibratory loads, or system dynamic loads depend on the. Root cause failure analysis seal gas filter dp transmitters calibration seal gas filter maintenance calibrated during 8k ppm found dirty with black carbon dirt soot filter replacement during 16k ppm dp across filter within range. Seal failures are the most common type of failure associated with rotating equipment. In the first case, tandem dry gas seals with intermediate labyrinth seals which ensures clean n2 or air to the secondary seal, will delay the failure of sec seal. A sealing failure analysis will help you continue reading sealing failure analysis. Dry gas seal systems for centrifugal compressors august 2, 2017 july 1, 2019 ct2 staff centrifugal compressor, dry gas seals, reliability, seals the faces of a dry gas seal can contact during slow roll if hydrostatic, or hydrodynamic forces are not adequate to achieve seal face liftoff. Centrifugal compressor wet seals seal oil degassing and.
Allowing your pump to run dry can be very damaging to a mechanical seal. A clean and dry separation gas is continuously injected into the barrier seal to protect the migration of lube oil from the outboard bearing housing. This intensive oneday course is designed to help enduser oem contractor personnel eit engineers working with turbomachinery such as centrifugal gas compressors used in process industries learn more about 7 major factors and respective root causes of failure of dry gas seals dgs of centrifugal gas compressors used in oil, gas and petrochemical industries. Introduction to failures failure of the mechanical shaft seal is the most common cause of pump downtime. Reliable support flowserve compressor seal specialists as single. The shaft seal is exposed to widely varying operating conditions. Gas emissions from wet seal centrifugal compressors have been found to be higher than dry seals compressors primarily due to the offgassing of the entrained gas from the oil.
The compressor dry gas seal has officially been put into operation for six months, it damaged twice and caused the device to unplanned shutdown, seriously affected the long term operation of the device. Common dry gas seal failures are discussed below along with their. The rca rootcause analysis is an important step after a seal failure. Under the right conditions, mechanical seals can experience thermal shock and shatter within 30 seconds or less. The first thing to do is to provide your seal vendor a gas composition so that they can carry out a gas analysis to determine if any liquid will drop out during settle out conditions. Dry gas seal systems for centrifugal compressors page 2. Troubleshooting mechanical problems for bearings, mechanical. Improperly starting the pump can cause the motor to trip and the shaft to twist causing orbital movement, resulting in internal parts contact, seal failure, and shortened bearing life. Elliott dry gas buffer systems are designed to api 614 standards.
Failure analysis and transformation of hydrogen compressor. Mar 23, 2019 dry gas seals may or may not provide positive gas sealing if the seal faces are damaged or distorted. This book presents a complete guide to the technology, from the principle of gas seal operation to lessons learned from actual field experience. Seal buffer gas pressure max process gas pressure 2. Aura reduces operational and transactional costs using a patented polymeric sealing device and can reduce leakage rates by up to 15 percent. For warming lubrication oil and maintaining bearings when the compressor is in storage, a contacting carbon ring provides a good restriction to minimize oil flow toward the dry gas seal.
Sensitivity to pressure is also a concern because this can cause heat generation, resulting in dry gas seal failure. Continuous seal condition monitoring across compressors. Case study on frequent failure of dry gas seals onepetro. An example of this was found in a gas pipeline station run by a leading company which was facing recurrent seal failures. Figure 7 shows the arrangement of a carbon ring separation seal in a dry gas seal cartridge. The single seal arrangement is used for moderate pressure applications, where small amounts.
On the damaged shaft seal, it is possible to observe what is damaged, but the reason for the damage must often be found on the basis of knowledge of the pump and the application. Overview dry gas seals are gaslubricated, mechanical, noncontacting, endface seals, consisting of a mating rotating ring and a primary stationary ring. Sometimes operating conditions change to become quite different from the specific conditions for which the seal was intended. Compressor is equipped with john crane make dry gas seals of type 28at. Emery johnson is the product specialist, dry gas seals, for eagleburgmann na. This case study represents the frequent failure of dry gas seal. For a more complete description of dry gas seal principles of operation, see shah 1988.
Seal gas filter dp monitoring mechanical failure operating condition material failure maintenance dry gas seal leakage. Lab analysis revealed the presence of iron in the process co2. Read more about the reasons for pump and mechanical seal failure in our. The development and introduction of dry gas seals solved several seal problems of compressor users. Request pdf analysis of historical dry gas seal failure data while proper design and maintenance of dry gas seals is a wellunderstood topic, dry gas seal failures are still relatively common. Analysis of historical dry gas seal failure data turbo. Since seals are a barrier between the process and the atmosphere, such failures are often likely to lead to environmental problems, and potentially a safety problem depending on factors such as the flammabilitytoxicity of the process fluid, the size of the.
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