INTERPLANT STANDARD - STEEL INDUSTRY

Transcription

1 INTERPLANT STANDARD - STEEL INDUSTRY IPSS STANDARD MAINTENANCE PRACTICE FOR PNEUMATIC OPERATED SHUT OFF VALVES No Corresponding IS Exists IPSS: Formerly-: (New Standard) 0. Foreword 0.1. Interplant standardization activity in steel industry is being pursued under the aegis of Steel Authority of India Limited (SAIL). This Interplant Standard has been prepared by the Standards Committee on Instrumentation and Automation IPSS 2:7, with the active participation of representatives steel plants, other concerned organizations and established manufacturer in the field, and was adopted on May, Shut off s are used to isolate the process conditions such as flow, pressure, temperature and liquid level by fully opening or closing the process parameter like steam, coal tar, oxygen, N2, COG, BFG, LDG and others as per the signal received PLC/DCS. The can be Ball Valve. Globe or Butterfly Valve The opening or closing of control s is usually done automatically by electrical / pneumatic s. Pneumatic solenoid s are used to control the opening or closing based on electric signals. These control signals, traditionally are 220v ac, 110v ac, 24 dc. Depending upon the condition condition, feedback is taken the DCS with help of proximity, micro, limit, magnetic and few others as per process requirement A shut off consists of four main parts namely: i) Valve s ii) Valve s DC solenoid iii) Valve s body iv) Valve feedback system 1. Scope The scope consists of inspection of all the pneumatic operated shut off s. i) Inspection guidelines ii) Running inspection (monthly) iii) Periodical inspection / maintenance ( basis) iv) Inspection format Page 1 of 5

2 2. Inspection Guidelines : Running Inspection Sl. No. Check Point Details 1 Instrument Air Line and its Quality 2 Air Filter Regulator and Gauges 3 Leakage of Actuator 4 Leakage from Valve Flanges 5 Leakage gland 6 Condition of the linkages/ couplings Frequency How to Check Criteria Action (if out of criteria) for presence of moisture and required pressure for the proper pressure required Physically check for for leakage gland misfit linkage No moisture to be present Indication of the pressure gauge leakage Physically check for No leakage should be to be observed Draining the drain value in instrument manifold supply air line Check the source of pneumatic air Check for the functioning of drier In the gauge by increase/ decrease the presence as per requirements Arrest the leakage by sending the same to MED Instrumentation Lab arresting the same by isolating the process with SOP If yes check for any increase in temperature. Make plan to arrest the same on day. The link / coupling has to be properly tightened with proper tools and tackles 3. Maintenance Guidelines: Sl. No. Check Point Details 1 Quality of Air 2 Line leakage of instrument air line Frequenc y How to Check Criteria Action (if out of criteria) presence of moisture any pneumatic leakage No moisture to be present any leakage Instrument manifold of the supply air by draining the drain Check the source of pneumatic air Check for the functioning of drier From the instrument manifold to the positioner I/P Page 2 of 5

3 3 Condition of AFR and its gauges 4 Protection for feedback enclosure box 5 Condition of Mounting Bolts of / power cylinder 6 Leakage in the 7 Protection from water ingress on 8 Condition of nuts and bolts of body 9 Leakage flanges of body 10 Condition movement 11 Leakage gland presence of moisture and dust feedback condition and its fittings whether it is loose or not Physically check for water protection is or not looseness of nuts and bolts not be any leakage movement stem leakage gland No dust or moisture to be present The feedback shall be properly sealed and properly tightened The nuts and bolts to be firm without any looseness not be any leakage If installed outside should be canopy should be Physically check for No jerk should be No leakage should be Whether the filter is clean by isolating the same on a day and cleaning filter Check for the condition increase/decrease knob and drain plug Check for any leakage of the instrument air in the DC fittings and its gauges Check whether the cable glanding is proper to avoid any water ingress. Check the condition of the fittings. tightening the same by SOP Arrest the leakage by sending the same to the MED instrumentation lab for checking the Install proper protection for the shut off tightening the same by SOP. arresting the same by SOP. Check the gland packing and lubrication if required as per OEM recommendation. If yes check for any increase in temperature Make plan to arrest the same on day Page 3 of 5

4 12 Condition of link rods and its linkages 13 Condition of key way of and shaft 14 Checking end limit 15 Checking volume tank 16 Checking solenoid 17 Checking complete that should looseness Check for any slip between the and the shaft Check for the contact wrt to the travel Close the pneumatic supply to the volume tank Give command from PLC Check for the movement by giving command from the PLC/DCS should be No slip should be Both the open and close limit should be enabled during operation Manually close and see that is one cycle of operation travel. Manually check whether the is opening/closing as per command Complete movement The link has to be properly tightened with suitable tools and tackles Set right without any slip as it shall lead to hysteresis Adjust the limit as per requirement with proper SOP in proper for line isolation Check for the air pressure in the solenoid The pressure volume tanks should hold when pneumatic supply is put off. Check for the NRV for its healthiness Make sure the process line is isolated during Check for voltage in the coil during Check for the open close condition as per requirement and adjust the feedback 4. Inspection checklist format : Fortnight basis Sl.No. Area Checkpoints Emarks if any 1 Air pressure for solenoid g/cm2 2 Leakage of instrument air line Y/N 3 Looseness of linkages Y/N 4 Leakage of gland Y/N 5 Leakage of flanges Y/N 6 Movement control smooth Y/N 7 Condition limit Y/N 8 Contact limit with striker Y/N Page 4 of 5

5 Check List for shut off on 5. Inspection checklist format: Shutdown basis Sl.No. Item to be inspected Ok / Not ok Comments 1 Pneumatic / hydraulic tubing leak tested 2 Instrument housing / covered 3 Wiring condition for solenoid and feedback 4 Open/close command proper 5 Open/close feedback proper 6 Air pressure for 7 Leakage in the process line are closing also State Check List State Description PLC input Local MI DCS Alarm Ok/Not Ok 0 1 Checking Transition Set point time delay in secs Actual time delay in Ok/Not Ok Comments if any: secs Page 5 of 5