Bellows failure

In cases where bellows failure would release flammable, toxic or corrosive liquids through the vent, a short nipple and elbow should be used to direct leakage to an open funnel which is piped to grade and ties into a catch basin or manhole with a sealed inlet connection. 

The most spectacular bellows failure of all time (Flixborough) was described in Section 2.4. Figure 9-8 illustrates a near-failure. 

Below -70°C and backpressures needing a balanced valve Pilot-operated, soft-seated valves are the only valid solution here. Balanced bellows valves are not acceptable at these temperatures due to the high risk of bellows failure ( cold working) and the risk of condensates freezing inside the bellows. This phenomenon is discussed in detail in Chapter 11. 

Failure of bellows can be detected by medium leaking via the bonnet vent. As this is not always evident and detection systems not always very reliable, people have become very inventive in trying to detect bellows failure by putting whistles on the bonnet vent in order to detect leakages from the bonnet vent. The bottom line, however, is that bellows are a very vulnerable but, for its correct operation, very critical part of a spring-operated SRV. Bellow balanced valves need more frequent maintenance or at least checking in order to assure proper operation. The system might have an SRV installed but with the bellows invisibly ruptured, the SRV has no purpose whatsoever. 

The next bellows failure is also caused by fatigue due to chatter, but this is also in combination with H2S/steam service and a 460 °C operating temperature (Figure 10.12). 

The next is also a bellows failure due to fatigue Indications of galling on the disc holder OD and/or guide ID are evidence that the valve has cycled frequently or has been chattering (Figure 10.13). 

VALVES. Figure 18 shows one of the seven valves used in the EBR-II working model system. The unique features of these valves are bellows seal with 10% bellows travel, spark plug probe to detect bellows failure back-up packing in case of bellows failure and a replaceable or removable bellows assembly that permits disassembly of bellows from valve body for cleaning. These valves are made up from stock parts and have been built in the ANL shop. There have been no failures. 

Air-operated bellows-sealed valves of special design are used. Metal bellows are enclosed in an all-welded housing to prevent solution leakage in the event of bellows failure. 

The Control plug supports the 12 absorber drive mechanisms, sleeves which house thermocouples for measurement of outlet temperature of each fuel subassembly and three selector valves with sodium sampling from each fuel SA for failed fuel location. Use of bellows has been avoided for CSRDM to extend the life of the mechanisms and to enhance reactor availability, as bellows failure has been responsible for replacement of CRDMs in reactors using this concept. V-ring seals are used between the stationary sheath and mobile assembly of CSRDM. The core thermocouples are located at a fixed distance of 90 mm from the top of the SA during reactor operation and no Core Cover Plate Mechanism (CCPM) is provided as in FBTR. Thermohydraulic analysis indicates that the thermocouples are immersed in their respective streams at all power levels thereby ensuring adequacy of temperature measurement. 

That only the southern and southeast outer perimeter of plant appeared to have been subjected to such great pressures indicates that the initial extent of the fuel air eloud had not penetrated extensively into the northern sections of the plant such as would have been the result of the simultaneous dual-bellows failure scenario. Furthermore, the determined center of the explosion, just immediately north of the main office building, and stated to have been at an elevation of about 20 to 30 m (Sadee et al., 1977), coineides elosely with the cloud development and its center of mass for the R4-only discharge. 

Exercising the Option of C02 Slippage to Mitigate Acid Gas Flaring During SRU Expansion Bellow Failure... 

Keywords Crack, Bellow Failure, Leak, C02 Slippage, Selectivity, SRU Management. 

At the time when SRU Incinerator bellow failure occurred, AGRU Train-1 2 were treating around 10,200 T/D of Sour Raw gas each with about 5,400 T/D of MDEA flow to Train-1 absorber fed over tray No.4 and 4,700 T/D of MDEA flow to Train-2 absorber fed over tray No.2 to meet the treated gas specification. This has generated an Acid gas feed flow of approximately 20,500 Sm /h to SRU. 

A report on sump water removal capability was issued jointly by the Savannah River Laboratory (SRL) and Idaho National Engineering L aboratory (INEL), and Sandia National Laboratory. The report scope includes calculations on flow to the minus 40-ft level during credible break size LOCAs to prove the existing sump pump capacity will remove ECS flow to the minus 40-ft level and to show that loss of pumping accidents are tolerable for small break LOCAs. This report, issued September 25, 1990, identifies the worst case LOCA as a Process Water pump suction bellows failure in loop 6 with four ECS injection paths (Reference 1). This report does not consider ECS throttling therefore, this LOCA condition will cause an eventual flooding of the DC motors. 

---