Piping installation safety

Boiler cost estimates include fittings, refractory, insulation and cladding for outdoor installation, internal piping, platforms and stairs, burner and flame safety equipment, economizer, force-draft fan plus drive and soot blowers. 

Safety improvements emanate from the re-evaluation of installation safety in light of the current standards, primarily in the areas of earthquake resistance, spray sodium fires and water and steam pipe rupture. In order to guarantee the main safety functions with respect to reactor shutdown, to the decay heat removal and to the confinement of radioactive materials, in all the aforementioned accidental operating conditions, the following safety improvements were required ... 

Install safety relief devices on piping and process equipment that may be overpressured. 

The design shall exclude the permanent installation of piping or other equipment which could inadvertently (e.g. by acting as a siphon) lower the pool water elevation below the minimum operating level specified in the interests of radiological safety and protection of the fuel. 

There are two basics methods for installing plastic pipe in trenches. Pipe with a large diameter is usually joined above ground and then lowered into a narrow trench. Smaller pipe, usually pipe with a diameter up to 8 inches, is often joined in a trench. This requires a much wider trench and it means that installers must be in the trench. When this is the case, appropriate safety procedures must be employed to protect the workers from trench failure and cave-ins. Before we get into deep details, let s discuss the basics of an underground installation. 

Radiation-Density Gauges Gamma radiation may be used to measure the density of material inside a pipe or process vessel. The equipment is basically the same as for level measurement, except that here the pipe or vessel must be filled over the effective, irradiated sample volume. The source is mounted on one side of the pipe or vessel and the detector on the other side with appropriate safety radiation shielding surrounding the installation. Cesium 137 is used as the radi-... 

Ground area and. space requirement.s. Comparisons of the overall space requirements for plants using air cooling versus water cooling are not consistent. Some air-cooled units are installed above other equipment—pipe racks, shell-and-tube exchangers, etc. Some plants avoid such inst ations because of safety considerations, as discussed later. 

The basis for design overpressure described in this section is related to the ASME Boiler and Pressure Vessel Codes and ANSI B31.3, Code for Petroleum Refinery Piping. Compliance with these codes is a requirement, or is recognized as the equivalent of a requirement in many locations. Where more stringent codes apply, the local requirements must be met. Therefore, local codes must be checked to determine their requirements. For example, some countries do not permit the use of block valves underneath pressure relief valves, unless dual valves with interlocks are installed. Also, in some cases, 20% accumulation under fire exposure conditions is not permitted, and accumulation allowed may be lower than the ASME Codes. In the United States, the ASME Code is mandatory, since it is a requirement under the Occupational Safety and Health... 

This section describes the requirements for the design and installation of pressure relief valve inlet and outlet piping manifolds and valving, including safety valve and flare headers. 

Credit for additional height of the flame center for multiple valve installations may be taken by clustering the safety valve discharge pipes to the atmosphere. The following procedure should be used for determining equivalent diameter and exit velocity to be used in the flame center calculation. Diameter and velocity are based on the total acmal area of the clustered vents. 

Figure 7-20. Recommended API-520 piping for safety relief valve installations. Reprinted by permission, American Petroleum Institute, Sizing, Selection and Installation of Pressure Relieving Devices in Refineries, Part ll-lnstallation, API RP-520, 3rd Ed., Nov. 1988.

It is not permissible to install an installation pipe in an unventilated shaft, void or duct (Regulation 18(5) of the Gas Safety (Installation and Use) Regulations). 

Venting, dusts, (deflagration), nomograph, API, 514-520 Relief valves, 400 Code requirements, 415, 420 Installation, 422, 429-434 Safety-relief, 400 Relieving pressure, 411-417 Resistance coefficient, K, (flow), 71, 72 Flow coefficient, Q, 81, 83 Pipe sizing, 83, 84, 86 Sudden contraction, 80 Sudden enlargement, 80 Tables/charts, 73-76, 77, 78-80 Valves, 81... 

A combination safety shower and eye wash station was installed in the laboratory. Although the engineering company recommended a very expensive chrome-plated unit, a much lower priced one which used plain galvanized pipe was chosen. Its performance was the same. The pipe was later primed and painted to match the laboratory furniture, another Saturday job for the laboratory operator. 

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