Piping maintenance safety

The final step in the plot plan arrangement is to space equipment and supporting facilities for operator and maintenance access, safety, piping flexibility and support, and platforming requirements. At this stage, the layout designer must rely on experience because the final information is not available for calculating... 

Storage areas for maintenance, janitorial, and other service organizations must be provided. Safety items such as fire extinguishers, firehose cabinets, safety hoops on permanent ladders, guard rads, shielding for acid pumps, clearance for electric panel boards, etc, are needed. Manholes and cleanouts for sewer pipes within the facility as well as in the landscape and parking areas should be provided. 

Before performing any inspection or maintenance on a flame arrester, the associated process eqnipment and piping shonld be taken ont of service or isolated. The work area mnst be proven by test to be free of any harmfnl gases or vapors. It shonld also be verified that all piping is clean and free of obstrnctions and debris. All plant, company, local, state, and federal safety and fire codes and standards shonld be followed. 

Layout spacings are also affected by other factors than safety. The space requirements of maintenance, repair works and proper performing of process operations has to be included into the process layout. Proper spacing around equipment is required to allow easy operation. Enough room should be provided for pipes, supports and foundations as well. 

Piping and Instrumentation Diagram Probability of Failure on Demand Process Hazard Analysis Pressure Indicator Protection Layer Preventive Maintenance Process Safety Incident Database Process Safety Management Pressure Safety Valve (Relief Valve)... 

Chapters 11-13 cover the selection and sizing of downstream disposal systems, reaction forces which require piping and vessel supports, maintenance, documentation and change management. Additional material is given in Annexes 1-8 and is referenced from the,text as required. This includes consideration of any safety factor to be applied to the calculated relief size. 

For mechanical systems (e.g. (a) and (b) above), it is important to ensure that, during maintenance, the safety functions of equipment are recognised. Otherwise, they may be replaced with unsuitable equipment. For instance, it is preferable for flow restrictors to use an orifice welded within a short length of pipe, so that it cannot easily be left out, rather than, an orifice plate that slips between pipe flanges. It is desirable to have some method of clearly indicating that such equipment has a safety critical function. 

The cheapest source of chlorine is the hazardous, yellow-green CI2 gas, supplied under pressure as a liquid. However, the supply of chlorine bottles (cylinders), the maintenance of a chlorinator (which permits the conversion of liquid chlorine into lower pressure gaseous chlorine), and the eductor and piping system is costly. It also requires first class health and safety handling procedures. 

Safety features for the tank include a pressure relief-valve system on the tank roof, to be opened when draining or adding to the tank contents. A bursting disc system also allows for pressure release in the event of pressure build-up. Amanhole providesaccessto the tank for internal maintenance. The product inlet line is standard nominal pipe size 1.5, schedule number 40S. This inlet is sized for the maximum production flowrates. The product outlet line is of standard nominal pipe size 6, schedule number 120. This line is sized such that a standard-size road tanker may be filled in 15 minutes. 

The Guidelines for Hazard Evaluation Procedures, Second Edition [5] also offers 45 pages of sample questions in its Appendix B. These questions cover process, (i.e., flowsheets and layout), equipment (reactors, heat exchangers, piping, and instrumentation), Operations, Maintenance, Personnel Safety, and other broad areas. 

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