FCC Valve Stuffing Box - Refiningcommunity
FCC Valve Stuffing Box from Design Best Practices to Field Troubleshooting Andrea Pusceddu Technical Director IMI Remosa - Italy
FCC Slide Valve ‣ FCC Slide Valve is a critical component for FCC Reliability. ‣ One of the most critical components of the SV is the stem stuffing box. ‣ Large Majority of emergency support from End Users is related to Stuffing Box issues. ‣ In virtually all cases, the root cause of the problem is in a improper lack of purging.
Stuffing Box Design ‣ Proper behavior of the Stuffing Box is ensured by a continuous purging (Steam, N2, Plant Air). ‣ The purging medium flowrate shall be continuously controlled. ‣ An excess of flow could damage the stem or the internals. ‣ Insufficient flow can lead to catalyst buildup, and backflow. ‣ A static Restriction Orifice (RO) is normally used to set-up the flow rate.
Stuffing Box Design Preformed Braided Graphite SECONDARY SET PRIMARY SET
Live Loading ‣ Live Load is achieved with a set of flat springs washers. ‣ Springs are contained in a two pieces housing that: ‣ ensures a perfect sealing on the stuffing box. ‣ provides an easy and failproof way to apply required preload. ‣ visually shows if the packing needs to be retightened.
Optimal Flow Velocity ‣ Main Purpose of the purging is to create a dynamic barrier against catalyst backflow. ‣ If trapped between the packing and the stem, catalyst may degrade surface finish and start a leak path, or build up a catalyst block. Optimal Catalyst Flow Internals Buildup Erosion ‣ On the other hand, an excess of velocity will accelerate catalyst particles in the stem premises, creating eroding jets that may damage internal components. ‣ In order to avoid both side effects in the same time it’s paramount to have a fine control of flow velocity! Vmin Vmax Flow Velocity
What if Purging goes wrong? (insufficient flow)
and what about if I have too much flow?
Purging Media Medium Pros Nitrogen It’s the most stable chemical Normally it’s an expensive solution element, does not react or oxidize. for the End User. Superheated Steam Cheap supply, no oxidation issues for graphite packing. Steam shall always be superheated and dry, condensation is a big issue, e.g. due to poor pipes insulation. Easily available. May trigger combustion (e.g. partial burn process) and accelerate graphite packing volume loss (oxidation). Dry Air Cons
Checklist Before Startup Verify that Purging Medium type and conditions match the Procedure Verify Restriction Orifice Size matches the Procedure Verify all valves along the pipe routing Verify Packing Preload (Live Load Gap) During Operation Daily Check the Purging parameters Weekly Check of the Packing Preload (Live Load Gap) Weekly Inspection of the stem surface cleanliness
Troubleshooting & Tips ‣ During Commissioning and first months of usage it’s normal to experience a reopening of the Live Load Gap. Simply re-tighten the gaps, no special tools are required. ‣ Do not underestimate the importance of a continuous purging. In some cases even a short period without the correct flow may jeopardize valve reliability. ‣ Remember that catalyst leakages are non reversable and self increasing process. Once a leakage is detected something it may be possible to stop it by increasing the Packing Preload, but this would not reverse any internal damage. ‣ Remember that once a leakage is visible, the catalyst already traveled across Primary and Secondary Packing! Prepare for an Emergency Sealing Attempt.
Emergency Sealant Kit A graphite based special compound can be injected in the Emergency Sealant Port using an high pressure hand pump, in order to stop or decrease the leakage in case of safety concern.
Base Purging Layout
Basic Purging Panel
Limitations of Static Purging Systems ‣ Static purging systems work as long as the purging medium and the process fluid matches the expected/nominal conditions (temperature, pressure). Outside this scenario the system loses its set-up: too much flow or insufficient flow. ‣ Malfunctioning can be detected only by human operators, depending on visual indicators installed in the purging systems (flowmeters, pressure gauges).
Active Purging System Layout OPTIONAL p inlet p outlet
Active Purging System
Conclusions ‣ Stuffing Box is one of the most critical components of an FCC Valve. ‣ Stuffing Box failures are hardly recoverable during service, but can be prevented with simple and easy checks. ‣ Active Purge System is the latest technology development in this field, and will bring an unprecedented layer of additional safety and reliability to your Process.
Thank You!
Stuffing Box Design ‣ Proper behavior of the Stuffing Box is ensured by a continuous purging (Steam, N2, Plant Air). ‣ The purging medium flowrate shall be continuously controlled. ‣ An excess of flow could damage the stem or the internals. ‣ Insufficient flow can lead to catalyst buildup, and backflow. ‣ A static Restriction Orifice (RO) is normally used
Stuffing Boxes Made to fit Dual Pack stuffing boxes, easy-to-install adapters allow fit to ALL industry stuffing box and flow-T types. Production Safety-Supply LTD. Model HT Stuffing Box Red Wing Stuffing Box Harbison-Fisher: Quick-seal box, "Opel" Harbison-Fisher: Injecta-Box Single Pac Hercules Stuffing Box Big Stuff Dual Pack Hercules
mounted stuffing boxes to the industry, which allow the stuffing box to be serviced from on top of the drive head without removing the drive head from the well. These types of stuffing box are shown in Hult Canadian patent applica tion 2,350,047 (the "Oil Lift Stuffing Box"). These top mounted stuffing boxes use a flexibly mounted "floating
mechanical integrity and sealing performance of stuffing-boxes valves. The results also demonstrated that an open and tapered angle on the internal wall of the housing is useful in improving the sealing performance of a stuffing-box. Keywords: Stuffing-box Valve, Sealing Performance, Micro and Nano fluids in porous media, Constitutive model
O-Rings O-rings for Stuffing Box, 12-Pack 16-170 16-170-516 Spare Screws Screws for Stuffing Box, 3-Pack 16-172 Lubricating Wipes Lubricates rod for easier insertion through stuffing box. Canister of 20 wipes, non-toxic, water-based. 15-WIPE Hex Wrench 3/16" Ball-nose hex wrench for 1/4" and 5/16" stuffing boxes 16-HW316 End Ferrule Repair Kit
Stuffing Boxes 20 Hydraulic Slickline Stuffing Box 21 EziLoad Slickline Stuffing Box 22 Liquid Seal Head 24 Tool Catchers 26 Hunting EziCatch Tool Catcher 27 EziCombo Tool Catcher / Stuffing Box 28 Open Hole Tool Catcher 29 Grease Heads 30 Cleanline Grease Injection Control Head 31 Hydraulic Grease Head Cable Cutter 32
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the flow rate and pressure. To select the correct valve to fulfill these functions properly, an outline of the different types of valves and their features is given below. Butterfly valve Butterfly valve and globe valve Butterfly valve and ball valve Butterfly valve and gate valve Check valve Gate valve Globe valve Ball valve Valve shaped like a
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