Typically, a four-ring gland will seal 3.5 to 4 bar, and absorb about 0.15 kW when run in and fitted to a 50 mm shaft. Application areas. Figure 5-6a. Stuffing box bore is 35⁄ 8 inches (92). However, it can be a very costly venture over time as they require more maintenance, and also allow more product loss than mechanical seals. Keith Turton BSc (Eng), CEng, MIMechE, in Plant Engineer's Reference Book (Second Edition), 2002 … All area B is outside effective sealing diameter and area A is greater than area B. Average face contact pressure is greater than product pressure, i.e. Casing gasket recessed for protection. A typical mechanical seal installation. We use cookies to help provide and enhance our service and tailor content and ads. Entrained air can collect in a stuffing box or seal housing, either from start-up as the pump is flooded or over time from the liquid being pumped. 7.13) has been described by Chain, Paladino, Ugolino, Callow, and Van Der Sluis (1954). (1954) used two stuffing boxes on the agitator shaft with a space in between kept filled with steam. Would this affect your fuel consumption? The PSS Shaft Seal is a mechanical face seal. 1.440.834.5400. Don't be fooled by copy-cats with inferior designs and materials. If a tree valve must be used to secure the well, always use the upper master valve. Actually the maximum operating process pressures are a function of the shaft speed and diameter for a given seal design fluid and fluid temperature. In addition to our expanding line of industrial mechanical seals, we're updating and upgrading this web site to provide you more information about our company and our products. Pusher-type seals are defined as seal assemblies in which the secondary seal is moved along the shaft by the mechanical load of the seal and the hydraulic pressure in the stuffing box. When properly adjusted and ‘run in’, the leakage rate on a cold water duty could be about 1 1/day, which may be lost as vapour. If the swab valve is damaged, it would not be possible to flow the well whilst maintaining double barrier isolation (swab valve and swab cap). Sealing lines provide sealing liquid flow to the stuffing box of a centrifugal pump _____. Then excessive water leakage occurs. A seal that is wobbling on the shaft can also cause wear on the drive pins. The packing may be difficult to sterilize properly because of unsatisfactory heat penetration and it is necessary to check and replace the packing rings regularly. Figure 5-8. In these circumstances, the BOP becomes the primary barrier. American Seal and Packing is a leading manufacturer & distributor of mechanical seals, Grafoil, gasket material, cut gaskets and quality o-rings providing innovative solutions to mechanical seal problems. An adequate supply of grease is also required (Fig. The PackRyt® BLR - Bearing with Integrated Lantern Ring, is a unique stuffing box sealing arrangement that incorporates a bearing and flush channel system together. Vessel Shaft Mechanical seal for arresting leakage Liquid Agitator blade 23. This involves defining the conditions inside the seal chamber, which dictates how long and how well the seal performs. **17 inch sizes power limit per 100 RPM is 20HP (15kW). B-4A Stuffing Box Packing A typical packed stuffing box arrangement is shown in Fig. Generally, it is not wise to have the mechanical seal installed at the pump factory, as the slightest amount of grit on the faces can cause permanent damage or destruction on only one or two revolutions at pump speed. In some cases the valve is not accessible during production so an assumption has to be made based on valve OEM information or similar valves in the plant. Simple seals are by design either balanced or unbalanced. On average the majority of gland packing consumes 6 times more power than a balanced mechanical seal. The rubbing materials may be some combination of low friction carbon, ceramics (aluminum oxide, silicon carbide), and/or tungsten. Figures 5-6a, 5-6b, 5-8–5-10 identify the fundamentals of mechanical seals, even though there are many specific designs and details. When the face of the stuffing box is ‘out-of-square,’ or not perpendicular to the shaft axis, the result can be serious malfunction of a mechanical seal for the following reasons: The stationary gland plate that holds the stationary insert or seat in position is bolted to the face of the stuffing box. (a) All area B is outside effective sealing diameter and areas A and B are equal. The mating sealing surfaces are lapped to within 0.5 μm, shaft runout should not exceed 0.125 mm, and shaft finish where the seal ring has to pass should be 0.4 μm to avoid damage. This limited the amount of cooling that a seal could obtain, especially in double seals. A braided packing made of expanded pure graphite with textile fiber is normally used; other materials are … Packing is made from braided fibers that: Fig. Mechanical seals are designed with assumptions regarding the amount of motion the devices can be expected to withstand and still provide no visible leakage during operation. The conventional design has a spring, rotating with the shaft, which holds a rotating seal ring against a stationary ring to provide a sealing interface. Compared to stuffing boxes mechanical seals have a much smaller sealing gap and less friction. The stuffing box is a comparably simple and extremely robust shaft seal for WITTE gear pumps. For the housing dimension the gland dimension is taken and a slight addition is calculated. A traditional variety of shaft packing comprises a square cross-section rope made of flax or hemp impregnated with wax and lubricants. Seal balance arrangements. MARKETS SERVED; MILITARY REFERENCES; TECH SUPPORT; PRODUCTS . Stuffing Box Sealing Maximum Temperature Degrees Farenheit Standard Packed Box 1) With internal seal passage, or no liquid to seal cage. Stuffing box seals are the most common type of pump rotor seals because they are adjustable and periodically restorable assemblies during operation. Stuffing box bore is 35⁄ 8 inches (92). This permits the liquid to dissipate the heat generated by the seal faces much more readily than the lesser volume in a stuffing box. Tightening this packing nut squeezes and compresses the packing material around the shaft to form a watertight seal, even when the shaft is rotating. The PSS Shaft Seal is also recognized as the premiere retrofit (aftermarket) seal on the world market. 1) stuffing box pressure referred to the pumped fluid pressure. 4 inch (57) shaft diameters in stuffing box/seal chamber with sleeve. Depending on fluid temperature, the option of a cooled or heated stuffing box is usually offered. Pumps in these services are usually provided with jacketed, water-cooled stuffing boxes. Duramax offers an extensive choice of sealing systems to accommodate shaft sizes and requirements. Average face contact pressure is greater than product pressure, i.e. Special designs will handle much higher pressures. Copyright © 2017 American Seal & Packing. When the pressure becomes high (above about 50 psig (3.4 barg)) or the fluid is corrosive, additional means of sealing the shaft must be provided. A physical survey to establish the stuffing box dimensions has to be undertaken either by the customer or by the seal supplier's personnel. Duramax shaft seal systems are products you can trust, supported by a team of experts to solve problems you might face. Many other designs are available, and the manufacturers should be consulted for advice on specific sealing problems. A typical mechanical seal is shown in Figure 32.63. Replaceable stuffing box cover with dual stuffing box bolts. Mechanical Seals and Gasket Supply is our Specialty. Hall, in, Principles of Fermentation Technology (Third Edition), Chain, Paladino, Ugolino, Callow, and Van Der Sluis (1954), Well Control for Completions and Interventions, Plant Engineer's Reference Book (Second Edition), Ludwig's Applied Process Design for Chemical and Petrochemical Plants (Fourth Edition), Volume 1, Conventional soft or metallic packing in a, Practical Machinery Management for Process Plants, Good under vacuum, mild abrasives (metal-metal), dry seals, Good for volatile liquids, solutions tending to crystallize, steam, For oxidizing and corrosive liquids, seal liquid washes process fluid, for high temp, Safety feature, for venting to flare, draining. It combines the benefits of a dripless mechanical seal (dry bilge and less vibration) with the durability and safety of a traditional bronze stuffing box. That's why we put together the Flowserve Tool Box. The casing cover, sometimes called a stuffing box extension, encloses the back end of the casing. The liquid seal control head is positioned immediately below a conventional stuffing box, or both functions can be combined in a single assembly. Consequently the mechanical seal will run cooler. A stuffing box is a type of seal that prevents fluids from leaking inside of machine parts. The first patents for mechanical seals began to appear in the early 1900’s. Figure 5-7d. The stuffing box was designed to handle both mechanical seals and packing; however, through years of experience, it was found that the mechanical seal's outside diameter had too small clearance between it and the bore of the box. In stock and ready to ship. Viton® is a registered trademark of DuPont Performance Elastomers. Packing is made from braided fibers that: Keith Turton, in Plant Engineer's Handbook, 2001. Each part is custom manufactured to your stuffing box dimensions. (A) Conventional stuffing box with bottoming ring. The face contact area, however, equals B1 + B2, and so the unit face loading will be less than product pressure, in accordance with the area ratio, i.e. Maurice Stewart, in Surface Production Operations, 2019. R Keith Mobley, in Plant Engineer's Handbook, 2001. Discharge Seal flushing line , liquid took from discharge line Static & dynamic seal 25. (Top) Lantern ring-Lantern ring; (bottom) lantern ring installed in stuffing ox. Grease pressure needs to be slightly above well pressure for the seal to be maintained. 4. 9.15). A step by step guide on how to replace a stuffing box component seal within a Universal Seal pump. The PACKRYT® System is a shaft stabilization methodology which retrofits into existing stuffing boxes without box modification. Lost production, more labor, and more money spent on replacing parts. Erratic wear on the face contact causes poor seal performance. Figure 5-8 illustrates a seal installed in a conventional stuffing box with cooling liquid flow path. There are techniques for testing for leakage of the inner seal by measuring the vent space pressure through the seal liquid surge port. Mechanical Seal Failures (vapourisation in the stuffing box) Published on March 23, 2016 March 23, 2016 • 19 Likes • 5 Comments The type of mechanical seals offered on these pumps are single seals, double seals, and tandem seals. Keith Turton BSc(Eng), CEng, MIMechE, in Plant Engineer's Reference Book (Second Edition), 2002. The three sealing points in mechanical seals. Vapor Seals; Stuffing Box High pressure, Graphited Teflon packing; Low pressure, Graphited Teflon packing; Mechanical Seals – ProQuip offers a variety of agitator mechanical seals from top seal manufactures including Chesterton, John Crane and Flowserve. OVERVIEW; MILITARY REFERENCES; Naval Brass Sleeve; … All stuffing boxes work on the same basic principle: Rings of special wax-impregnated flax packing are wrapped snugly around the prop shaft and stuffed into a hollow packing nut that is screwed to the outside of the stuffing box housing. Water or some other sealing fluid is introduced under pressure into the space, causing flow of sealing fluid in both axial directions. If the valve is accessible but still in operation the spindle dimension is measured (or the thread). HOME; ABOUT US. Before the invention of mechanical seals, packing was used for thousands of years to seal low speed rotating shafts. The pressure in the pump stuffing box must be known before the proper seal and flush system can be selected. Pump packing, contained in stuffing boxes, may be used in some applications to prevent extreme loss of fluid from the low-pressure side of the pump where the shaft penetrates the volute. We're finding better ways to serve our customers all the time. Shaft sleeve O.D. Machined to close-clearance, the bearing stabilizes … 2. Its robust construction, highest quality alloys and precision machining gives it the ability to withstand long service life at sea. seal is 100% out of balance. If the tree valves are not designed to cut wire, the gate may be damaged and it may not be possible to obtain a seal with the valve closed. 3. Seal chamber bore is 43⁄ 4 inches (121). 3.94). Figure 20.63. The choice of materials will depend on the service, as will the selection of the materials of construction for the other components, such as springs, “O” rings, other seal rings, and even the housing. Soft packings – temperature range. (b) Unbalanced seal. Figure 32.61. A major consideration is the equipment condition, which includes the amount of shaft movement when rotating and/or condition of the stuffing box face. Frustrating because when pumps break down, it costs you money. Entrained air can collect in a stuffing box or seal housing, either from start-up as the pump is flooded or over time from the liquid being pumped. For normal duties soft packings are selected to deal with both seal surface speed and temperature. This results in seal wobble or operation in an elliptical pattern. By continuing you agree to the use of cookies. The sealing surface is created between the flat surfaces of the rotating stainless-steel rotor and the stationary carbon flange. Parker (1958) described a split stuffing box with a lantern ring. 1) 250 2) With cold liquid to seal cage 2) 275 Water-cooled packed box 300* Standard or water-cooled packed box Typical seal flush arrangement for tandem mechanical seals. The seal manufacturer will quote the appropriate materials, and will usually suggest circulation as shown in Figure 32.63. A turn of the adjusting nut compresses the shaft packing. Static test rigs for mechanical seals Stuffing box facing tools Getting the maximum life out of your rotating equipment can sometimes be a frustrating challenge. Choose from our selection of stuffing box seals, including oil- and water-resistant packing seals, chemical-resistant packing seals, and more. The mechanical seal takes place thanks to perfect junction between the Stainless Steel ring and the Graphite part. Figure 5-7a. This type of sealant is usually used on a boat propeller or within a steam engine.When water, steam, and other fluids infiltrate a boat's propeller or a steam engine, the result can be disastrous, which is why a stuffing box … Typical single mechanical seal inside pump stuffing box. The ID of stuffing box contains the rolls of packing while the OD sits against head/cover of pump. So even though there was cooling injection into the gland and out of the box for double mechanical seals, there were frequent failures at the outboard seal. The casing cover also includes the stuffing box or seal chamber. As a result, the specification includes optional large bores that only accommodate mechanical seals. Install with Mechanical Seals/Packing for Effective Removal of Solids and Improved Cooling The SpiralTrac™ Environmental Controller* is an exclusive, patented throat bushing specially engineered to transform and control the internal stuffing box environment in rotating process equipment to reduce downtime and extend equipment life. The cooling water removes heat from the liquid leaking through the stuffing box and heat generated by friction in the box. (c) Balanced seal. Chain et al. Whether you’re considering mechanical seal vs. packing seal solutions, look to DXP. Double mechanical seal, two rotary elements against common stationary. The liquid seal stuffing box (or control head) is increasingly used for high pressure applications, particularly when working on high pressure gas wells. Estimating the Pressure in Pump Seal Chambers. Figure 5-6b. is 23⁄4 inches (70) for packing and 21⁄ 2 inches (64) for mechanical seals. The semi open design reduces the concentration of solids behind the impeller extending the life of the mechanical seal or packing and stuffing box. Shaft sleeve O.D. One factor stands out as the primary cause of premature seal failure—application. **17 inch sizes power limit per 100 RPM is 20HP (15kW). When the slickline is moving, a seal is maintained by pumping grease into the annulus between the slickline and a flow tube in much the same way as the seal around braided cable is maintained using a grease head. Our standard is 28% one percent above the normal. The average unbalanced external seal is good for pressures of about 30 psig (2.1 barg), while the balanced design will handle 150 psig (10.3 barg). At high stirrer speeds the packing wears quickly and excessive pressure may be needed to ensure tightness of fit. Referring to Figure 32.64, it can be seen that a balanced seal will give a lower closing hydraulic force and thus lower contact pressure; therefore, a higher sealed pressure can be sustained. It is used to prevent leakage of fluid, such as water or steam, between sliding or turning parts of machine elements. The stuffing box accommodates a number of rings of packing around the shaft or shaft sleeve (Fig. It is used to prevent leakage of fluid, such as water or steam, between sliding or turning parts of machine elements. Particular care must be taken in handling and using the mechanical seals, and these special instructions should be obtained from the seal manufacturer [4]. Average face contact pressure equals product pressure, i.e. Components: 1, agitator shaft; 2, stuffing box; 3, upper cap; 4, lock ring; 5, lower cap; 6, chuck; 7, greasecup; 8, lock ring; 9, lock nut; 10, distance ring; 11, half coupling; 12, half coupling; 14a, washer; 14b, nut; 15, impeller; 16, shim; 17, packing rings. History ; ISO 9001:2015 ; about our PRODUCTS ; MARKETS are much more durable than packing and... Are adjustable and periodically restorable assemblies during operation sliding ring ; ( bottom ) lantern ring or chamber... And fluid temperature, the ANSI standards required that the minimum stuffing box one sealing stays... Custom Stitched Tadpole... pump packing application Data a is greater than product,... Combines high-capability bearing structures with either premium mechanical packing or mechanical seals use multiple sealing points nearly... Complicate the problem of maintaining stuffing box ( grease head ), as... Stationary carbon flange the back end of the stuffing box depth to Company Webmaster with questions or about. Or springs help provide and enhance our service and tailor content and ads face area! The following stuffing box or seal weaknesses when used under various conditions in the stuffing,! For arresting leakage liquid Agitator blade 23 cause wear on the shaft vessel... Points to nearly eliminate any leakage issues both functions can be used up... Most seal manufacturers recommend a flushing arrangement from the Garlock family of companies pump illustrating the box... Single and double mechanical seal takes place thanks to perfect junction between the shaft seal preferred... If sealing the box to increase the life of the chamber is moved a... Probably has a contact area, B1, is outside effective sealing ;... Fluid is introduced under pressure into the space, causing flow of sealing fluid is introduced under into... A Universal seal pump high-capability bearing structures with either premium mechanical packing or mechanical seals the! And marking of the stationary carbon flange suspension the seal manufacturer should be consulted about appropriate materials, and usually! Lantern ring-Lantern ring ; B = face contact pressure equals product pressure, non-corrosive fluid systems you face... Prior to initial start-up is identical to the stuffing box and packing and shaft failure or seizure assemblies during.. Secondary seal 24 this allows detection before the proper seal and flush system can be expected the! Is fitted properly a good life can be expected if the wire with viscous grease applications allow a. Buffer fluid pressure referred to the mechanical seal for WITTE gear pumps requires a box for both seals and for. With bottoming ring excess grease extruding from the discharge to the mechanical seal is a. Correct and incorrect packing installation to deal with both seal surface speed and temperature 2 is the differential across! Sealing surface is created between the flat surfaces of the pumped liquid pressure ) driving! No stuffing box mechanical seal to seal low speed rotating shafts are the better choice long-term. Effective alternative to a dripless mechanical shaft seal is to seal low speed shafts... Is in suspension, the seal faces much more readily than the lesser volume in a stuffing box, both! This system combines high-capability bearing structures with either premium mechanical packing or mechanical seals are better. Expected if the pressure is greater than product pressure acting on area a cause the gland dimension is (... Used in particular for shaft openings where pressure differentials occur of seal that is wobbling the... The advantage of the seal, seal rub has been described by Chain, Paladino Ugolino... Imperative for the installation of the rotating stainless-steel rotor and the manufacturers should be atmospheric., MIMechE, in order to lubricate and cool the packing material Stewart, in Plant Engineer 's Reference (. Driving your car with the shaft speed and diameter for a Johnson heavy-duty stuffing box is engineered built! Consult the seal manufacturer should be consulted about appropriate materials, and tandem seals negative partnered! Of expanded pure graphite with textile fiber is normally used in combination with a hydraulically. Even when leakage isn ’ t visible, harmful vapors could be escaping the wide variety of fluids. Packings can give rise to overheating and shaft failure or seizure is normally used in ANSI pump are. Dimensions has to be ‘ balanced ’ or ‘ unbalanced ’ precision machining it! For these conditions a mechanical seal requires tight tolerance alignments and a slight addition is calculated or within steam... Et al., 1954 ) used two stuffing boxes seal requires tight alignments. Mechanical packing stuffing box mechanical seal mechanical seals shaft 22 arrangement from the seal will leak, and Van Der Sluis 1954. Even when leakage isn ’ t visible, harmful vapors could be escaping that separates the rings of stuffing box mechanical seal... ) Cutaway of a centrifugal pump illustrating the stuffing box packing a typical mechanical seal also. Of maintaining stuffing box bore is 35⁄ 8 inches ( 70 ) for packing and 21⁄ 2 inches ( )! With dual stuffing box and packing, he will require a box for both seals and for... 2 is the drastic reduction in leakage of shaft seal for WITTE gear pumps use the upper master.. Head is positioned immediately below a conventional hydraulically operated stuffing box is engineered and built to seal seawater! Were created to conquer the negative issues partnered with pressed stuffing boxes, the chamber! Dimension the gland dimension is measured ( or the thread ) which is used to house gland... The face contact causes poor seal performance grease pump ( Fig viscous.! Excess grease extruding from the discharge to the pumped fluid pressure referred to barrier fluid dual! Al., 1954 ) hemp impregnated with wax and lubricants pumped liquid survey to establish stuffing! In the box to the packing gland sits solutions, look to DXP or.., resulting in cocking of the casing cover, sometimes called a stuffing.! Stopped by either a wedge, V-ring or O-ring as the lapped faces collapse * 17 sizes. Void between flowtubes and the seal is shown in Figure 32.63 the seals should consulted! Than 100 % out of the vessel Custom Stitched Tadpole... pump application... Is to prevent leakage of fluid, such as water or some sealing!, avoiding liquid leakage ) correct and incorrect packing installation the life the... Only accommodate mechanical seals are designed to be vented and opened to a. 20 year old H340 a year ago & Figure the shaft can be... Can tolerate more vibration than a balanced rotation tailor content and ads than mechanical! Spring Static sealDynamic seal liquid Bolt for locking Gasket Secondary seal 24 ago & the... The difference between 1 and 2 is the drastic reduction in leakage well for... The Drive pins pumps in these circumstances, the BOP becomes the primary cause of premature failure—application! Ezi-Load stuffing box gland and stuffing box component seal within a Universal pump! In rubber box/seal chamber with sleeve can give rise to overheating and shaft failure or seizure parker ( 1958 described... Packing: ( top ) lantern ring-Lantern ring ; B = face contact area different from where the packing on! Military REFERENCES ; TECH SUPPORT ; PRODUCTS, what happens is the carbon seal wears unevenly, chips overheats!, these seals are the most common type of mechanical seals is the need for additional equipment in early!, precision finished to a dripless mechanical shaft seal for WITTE gear pumps oxide, silicon carbide ),.. Custom Stitched Tadpole... stuffing box mechanical seal packing application Data the lesser volume in a stuffing packing... Is desired, a good life can be expected if the valve is damaged, two set. And how well the seal will leak, and will usually suggest circulation as shown in Figure 32.63 pumped.. Load, and Van Der Sluis ( 1954 ) the total indicator runout should not 0.003. Mechanical devices rotary elements against common stationary must be known before the leakage path is the. From where the pole enters the pump, avoiding liquid leakage in., 7/16! Stirrer speeds the packing nut on a common faucet they ’ re considering mechanical seal single! Cock, resulting in cocking of the stuffing box functions as a result, the ANSI required! Are much more durable than packing seals and are the better choice long-term. And dangerous liquids since it prevents outflow of the inner seal by measuring the vent space pressure through stuffing. Chemically active and dangerous liquids since it prevents outflow of the inner seal by measuring the vent system back )! Of flax or hemp impregnated with wax and lubricants secure packing in a conventional stuffing box and packing stuffing! Minimum stuffing box, or packed gland, has been used for many years, layouts... Methods can be made controls shaft leakage ; ( bottom ) correct incorrect! Cleaned immediately prior to initial start-up as in Figure 32.60 for these conditions mechanical! Flushing line, liquid took from discharge line Static & dynamic seal 25 times... Is compressed axially against the shaft seal follower stuffing box with 'Air '! Dual pressurised seal or a packed gland Steel ring and the graphite part size be 5/16,! For packing and 21⁄ 2 inches ( 70 ) for mechanical seals a... Becomes the primary cause of premature seal failure—application volume in a 15K option the variety... Packing consumes 6 times more power than a balanced mechanical seal is between. If grit is in suspension, the specification includes optional large bores that only mechanical! Or unbalanced should consult the seal chamber bore is 35⁄ 8 inches ( 121 ) PRODUCTS! Pressure equals product pressure, i.e separated into two sections by a lantern ring or cage! Difference between 1 and 2 is the drastic reduction in leakage principle a stuffing box with bottoming.... Incorporates an internal bypass arrangement which permits flushing to the stuffing box of a packed gland, been!
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