api 610 mechanical seal code price

A seal code is an abbreviated method of communicating basic specifications for the mechanical seal. Sadly, the seal code has been changed with every edition of API 682.  Fortunately, the new code, described in API 682 4th Edition Annex D, is the best to date and includes some concepts and codes from the historical API 610 seal code. The new code uses eight fields:

API 682 4th Edition was the first edition to include materials in the description and in many ways represents a combination of API 682 coding and the old API 610 codes.

4th Edition coding comprises four sections, some being sub-divided.  The table below shows the construction of a typical seal code, it is intended to accurately describe the seal and seal system being implemented in a given application.

T:  Seal type A, B or C per API 682 4th Edition definitions.  For dual seals using different inner and outer seal types, show both types using the format inner/outer.

Note that the codes used for Design Options are the same as those used in API 610 for materials that are included in both systems.  On the other hand, some materials cannot be specified because API 682 does not recommend them.  Such materials must be specified with an “X”.

For many years the pump standard API 610 contained a mechanical seal coding system which became widely used in industry. This coding method provided a reference to the nomenclature and features used with mechanical seals that were current during that time period. While this coding method is obsolete it still is still being used in some areas of industry. It is presented herein as a historical reference only.

A very commonly used code was BSTFM which translates to a balanced single seal with throttle bushing in the gland plate.  Gaskets would be FKM (fluoroelastomer).  Seal faces would be carbon vs nickel bound tungsten carbide.

P = plain, without throttle bush T = throttle bush with quench, leakage and / or drainage connection A = additional/ auxiliary seal (has to be stated)

4th letterstationary seal ring gasket, seal ring to sleeve gasket 5th letter --- ring 1 means seal ring ,ring 2 means mating seal ring Note seal ring ---seal face

Example for sealing and material code: BSTFO = balanced, single-acting mechanical seal with throttle bush, with dynamic and static secondary seals (O-rings) made of FKM and seal faces/ secondary seats made of tungsten carbide against silicon carbide

In a construction using C-6 material there will typically be 400 series stainless steel wear rings in the pump. The pump manufacturer will harden the 400 series rings so that there is at least a 50 Brinell hardness differential between the impeller and casing wear rings which helps prevent galling between the two rings during operation. Running clearance on these rings can be quite high at an elevated temperature. API 610 recommends running clearances greater than the pump OEM manufacturer’s clearances, especially as process temperature increases. High running clearances can provide improved reliability over time. As dry running a pump with metallic rings installed can cause catastrophic failure to the pump in less than one minute, special measures should be taken to prevent dry running the pump when metallic wear rings are installed.

Today there are a number of options on wear ring materials for customers to choose from in lieu of the traditional metal-to-metal ring combinations. Over the past two decades there have been many composite thermoplastic wear ring materials that have been introduced to the market. These composite materials are typically used on the stationary casing wear ring component. The composite material is installed inside of the metal ring as shown here. Composite material is also recommended for the stationary center bushing component on the API 610 BB3 design. Most composite rings can operate up to 500°F, allowing it to operate in most Boiler Feed Water applications.

With a composite wear ring on the stationary ring, running clearances can be taken to much tighter values, when compared to a metal-to- metal ring clearance. For example, the API 610 requires a .020” diametrical running clearance on a ring that is 8.000 inches to < 9.000 inches in diameter. Composite wear rings can accommodate a .011” diametrical running clearance on that same ring dimension. This ultimately improves the efficiency of the pump. In addition to its ability to run a tighter clearance, the composite ring also has a low coefficient of friction. This low coefficient prevents excessive heat buildup during an upset or temporary dry run condition. There are many case studies in the industry which show customers who have prevented a catastrophic and costly pump failure by having composite stationary wear rings installed on their pumps.

Composite rings come at a price. They can often add $15,000-$25,000 to the cost of a large API 610 BB3 pump. I will add that not all composite wear rings materials are created equal. Some will have different radial thermal expansion properties than others. It is encouraged that a pump subject matter expert conduct research before one decides on the type of composite ring material to use. Finally, caution is strongly recommended if using composite wear rings material in fluids with high solids content. If there is heavy scale or high solids in the boiler feed water, it is best to stay away from the composite ring materials. The thermoplastic base material can wear quickly in a high solids environment.

OH–Overhung pumps– The impellers of these pumps protrude from the bearings. The support has to take care of all forces, e.g. the overhung mass and the rotor dynamic and hydraulic forces. The impellers of these pumps can be mounted either horizontally or vertically. Its advantages are a single bearing housing and a single seal or packing, but an overhung impeller load is a disadvantage.

The casing can be either axially or radially split, with radially split designs found in tougher applications, such as API-610, where a large gasket area of the axially split design could be a concern for leakage. In fact, axial load is nearly completely eliminated due to impeller symmetry.

(VS) Cantilever– a cantilever design in which only the impeller and casing are submerged in the tank or sump. All joints, including seals, bearings, bushings, and suction check valves, are located out of the fluid. This design is ideal for moving slurries and abrasive solutions that could degrade or interfere with submerged joints.

End Suction Pumps–A straight shot-no turns and bends-is the most efficient way to bring the flow to the impeller, and such designs are called end-suction. In the back, a mechanical seal or a set of packings separates the fluid from leaking out. Following the seal, two bearings support the entire rotor (impeller, shaft, sleeves).

For end-suction designs, the impeller is cantilevered against the inner bearing. On the positive side, there is no restriction to incoming flow, which would be caused by placing one of the bearings at the front side-also called a between-bearing design. Cantilevering the impeller against the inner bearing also helps efficiency and makes the design simple and less expensive (with only one seal).

However, a long cantilevered rotor is prone to deflections, which may overload the bearings and cause seal failures. For this reason, rotor stiffness is an important factor, and designs with bigger shafts (D) and lower overhung length (L) tend to be more reliable. The factor L3/D4, a coefficient of proportionality between force and deflection, is a good measure of comparison between similar designs. The lower the L3/D4, the more robust the rotor-which results in better resistance to deflections.

The API OH1 is a horizontal, foot mounted, single stage, overhung pump with end suction. The pump is mounted to a baseplate and driven via a flexible coupler.

After more than five years of planning, the American Petroleum Institute (API) is preparing to release the 4th edition of API Standard 682 (ISO 21049:2011). The API 682 standard, which dates back to 1994 and is formally known as Shaft Sealing Systems for Centrifugal and Rotary Pumps, offers specifications and best practices for mechanical seals and systems to pump end users.

The standard’s latest edition began to take shape in 2006, when API formed a 4th edition task force to respond to end users’ questions and comments about previous editions. The task force soon realized that major changes, including reorganization and editing, would be necessary. While addressing every aspect of the resulting 4th edition (which is more than 250 pages long) would be impossible, this article summarizes the standard’s main points.

Those who use API 682 should understand the standard’s scope and remember that the standard does not include specifications for equipment outside that scope, such as engineered seals or mixers. Another important but often misunderstood point is that API 682’s figures are illustrative and not normative in their entirety.

For example, one of API 682’s figures shows a fixed throttle bushing combined with a rotating Type A seal, but seal manufacturers do not always have to combine these two components. The standard provides normative details in clauses and tables to help purchasers distinguish between requirements and suggestions.

The 4th edition continues to divide seals into three categories, three types and three arrangements. For all practical purposes, seal manufacturers can combine a seal’s component parts into nearly any orientation or configuration. Each orientation and configuration has advantages and disadvantages with respect to certain applications, performance and system disturbances.

Before the 4th edition, API 682 did not specify a minimum clearance between the inside diameter of a stationary seal part and the outside diameter of a rotating seal part. The 4th edition specifies this minimum clearance—typically the clearance between the sleeve and the mating ring. The specified clearances are representative of standard clearances that end users have used for decades. End users should not consider seal components to be “shaft catchers” to restrict shaft movement. The minimum clearance specified in API 682 also applies only to equipment within the standard’s scope. Equipment outside that scope, such as non-cartridge seals, older pumps, non-API 610 pumps and certain severe services, might benefit from larger clearances.

The new standard also updates the default bushings for the gland plate for the three seal categories. Fixed throttle bushings are now the default for Category 1 only, while floating bushings are the default for Categories 2 and 3.

While the 4th edition features the recommended seal selection procedure from the standard’s first three editions, it adds an alternative selection method in Annex A. Proposed by task force member Michael Goodrich, this alternative method recommends using material data sheet information to select a sealing arrangement.

Plans 66A and 66B are new to the standard, although end users have used them previously in pipeline applications. These plans detect and restrict excessive leakage rates in case of an Arrangement 1 seal failure.

The 4th edition has revised the data sheets in Annex C extensively to make them the same for all seal categories. Only two data sheets are included in the 4th edition—one in metric units and one in U.S. customary units. The new edition also folds Annex J into Annex E.

Previous editions of API 682 required metal plugs and anaerobic sealants when shipping new or repaired cartridges. After much debate, the task force decided that threaded connection points should be protected with plastic plugs for shipment. These plastic plugs should be red and have center tabs that operators can pull easily to distinguish the plugs from metal plugs. Shippers should also attach yellow warning tags to the plugs to indicate that end users need to remove the plugs before operation.

Although tutorial notes are scattered throughout API 682, this edition expands the tutorial section, Annex F, from seven pages to 42 pages. The expanded annex includes illustrative calculations. In particular, users interested in systems such as Plan 53B will find Annex F to be useful.

The 4th edition of API 682 is the product of more than 20 years of discussion, debate, usage and peer review. It includes a strong set of defaults and is by far the best and most logical starting point for mechanical seal and systems use. Equipment operators should take the time to familiarize themselves with API 682 to get the most out of this comprehensive standard.

Whenever a new edition of global specifications [e.g., International Organization for Standardization (ISO) and the American Petroleum Institute (API)] is released, there is usually massive confusion surrounding understanding explicit details of the key changes and why they were made. This article addresses five areas of changes that deal directly with pump reliability and maintainability, along with highlighting other various changes incorporated in API Standard 610 12th Edition, Centrifugal Pumps for Petroleum, Petrochemical and Natural Gas Industries, published in January 2021.

Background.API documents are typically updated on a 5-yr interval. API 610 12th Edition had a release date of January 2021, close to 11 yr after the published 11th Edition, primarily due to key items which required some additional time to resolve. The API 610 taskforce began working on this update in 2006. The group addressed the latest developments for rotating equipment, reliability issues, industry issues and proposed changes based upon proven, sound engineering and operating practices. Collaboration with other industry groups such as the Hydraulic Institute, the International Electrotechnical Commission (IEC), the National Electrical Manufacturers Association (NEMA) and ASTM ensured that this document reflected their latest updates. It should be noted that the API 610 12th Edition standard is no longer co-branded with ISO. The 9th, 10th and 11th Editions of API 610 were co-branded as ISO 13709.

The time required for the pump manufacturing industry to incorporate the changes to API 610 in the 12th Edition into their pump designs is difficult to determine. Historically, previous editions of API 610 have transitioned into worldwide usage over about a 2-yr period. Engineers generally will embrace certain changes to API 610 12th Edition because of the benefits presented by these changes, especially regarding the impact on pump reliability. The rest of this article highlights key changes in the standard, with some background explanations.

The annex contains sections for definition; selection criteria for pressure boundary and rotor; design considerations for pressure boundary components, impellers, diffusers or volutes, shaft seals, bearings and bearing housings; materials; manufacturing; and testing guidelines. Product reliability and maintainability is critical for these high-energy pumps. Examples of special purpose pumps are:

For high-energy pumps, every aspect of the design requires careful review, including rotor stiffness, distribution of residual stresses in metal-to-metal sealing surfaces, determination of deflection at critical fits and the establishment of proper running clearances. Performing structural analysis of impellers and diffusers (or volutes) is essential as is determining the proper net positive suction head (NPSH) margin based upon incipient NPSH (NPSHi), not just the generic 3% NPSH3. Especially for new designs, finite element analysis (FEA) of the bearing housing should be done to carefully determine the types of bearings to use. Lastly, the ability to easily assemble and disassemble impellers must be taken into consideration. As for manufacturing requirements, patterns and rigging should provide sound castings while non-destructive testing of highly stressed areas should be performed.

Introduction of API RP 691 Risk Based Machinery Management.API 610 12th Edition now refers to API RP 691—Risk-based Machinery Management—by means of bulleted paragraphs whereby the purchaser needs to advise the vendor when this recommended practice document is invoked. API 691 defines technical readiness levels (TRL) for machinery, with TRLs ranging from conceptual, prototype equipment (TRL 0) to well established, field-proven machinery (TRL 7). When API RP 691 is invoked, the vendor is to advise the purchaser of the TRL of the equipment being offered. API 691 defines high-risk machinery as machinery that handles hazardous liquids or gases, services operating at temperatures of more than 177oC (350oF) and operating pressures of more than 80% of maximum allowable working pressure (MAWP), services operating at temperatures of more than 204oC (400oF), components with TRLs less than 7, liquid services operating at pressures higher than 41.4 bar (600 psig), and liquid services with specific gravity less than 0.5.

API 610 11th Edition required a 20-yr minimum service life. This requirement was replaced in the 12th Edition with requiring only “field proven” equipment to be consistent with other API standards and with the API standard paragraphs. This eliminated any inferred equipment warranty issues.

For several past API 610 editions, a continuous rising to shut-off head curve was mandatory for all pumps. The 12th Edition changed this to be a bullet item for customers to select when they want rising-to-shut-off head curves. However, a note in this bullet paragraph clearly states, “pumps with continuously rising head curve are preferred for all applications, but this is not possible with all pump types.” An example of this is low-specific speed pumps (typically low-flow/high-head, high speed pumps, which have slightly drooping curve shapes, and pumps with multiple radial blade (Barske) design impellers. For pumps operating in parallel, in addition to a minimum 10% rise-to-shut-off mandate, the 12th Edition requires pumps with discharge nozzles larger than 3 in. (80mm) within the preferred operating flow region, to have head values within 3% of each other. These stipulations ensure one pump will not “push” the second pump to shut-off.

Important changes to the API 610 data sheets were made to address all alternate hydraulic operating points: rated and normal (same as before); however, now three additional operating points for customers to advise. These could be for handling a different liquid (as typically found with pipeline pumps or tank farms) or even liquids used to flush pumps during maintenance periods. Most important is that the driver (usually electric motor) is selected to handle the power requirements to handle all these operating conditions, which may have large differences in specific gravity causing an increase in Kw (Hp). Besides data sheets, the 12th Edition introduces a data list, which includes all data found on the data sheets; however, in a tabular form to compile all data into a neutral format to support electronic data exchange (EDE) among contractor, end user and pump manufacturer to minimize possible errors in transposing numbers among all parties.

Pipeline services are characteristic of pumping products with lower product temperatures vs. medium to hot temperature liquids found in refinery services. Because of this, API 610 12th Edition now states the limit for using sleeve/sleeve-ball bearings in pipeline pumps as 8 × 106 kW/min (10.7 × 106 hp/min) after which hydrodynamic radial and thrust bearings are to be used. The 12th Edition also states that for pipeline pumps, with energy density values between 4 × 106 kW/min (5.4 × 106 hp/min) and 8 × 106 kW/min (10.7 × 106 hp/min), hydrodynamic radial bearings shall be used with either rolling-element or hydrodynamic thrust bearings.

New to the 12th Edition is the mandate for shaft guards. Previous API 610 editions, including the 11th Edition, addressed only coupling guards. Inputs from multiple refineries indicated that safety organizations were pointing out that the area between the pump casing cover and the bearing housing has an exposed shaft area that should be covered (FIG. 2). More specifically, this is the shaft area where the mechanical seal gland is located. Furthermore, the drive collar adjacent to the cartridge seal has set screws, which could be a concern if someone placed their hand in that area during pump operation. Basic design for refineries addresses venting to prevent accumulation of seal emissions and a port to measure emissions, whereas for pipeline services a different approach is typically taken.

Options for other designs such as open top-plate, non-grouted and non-grouted with gimble mounts are addressed. The purchaser is to advise which design is required. Designation for Annex D, which provides pre-engineered baseplate sizes, has changed from being normative to informative based on the industry feedback that with today’s enhanced computerized layout of equipment by engineering, procurement and construction (EPC) companies and the quick turnaround by vendors to generate pump general arrangement drawings, this mandate for standardized baseplate sizes has diminished. The 12th Edition states baseplates may have Annex D dimensions if driver, pump size, auxiliaries and seal flush piping properly fit.

A new requirement for OH2 pumps addresses the location for placing auxiliaries in the front region (adjacent to pump suction nozzle area) of the baseplate. This is a major change that improves accessibility for maintenance of single-stage overhung pumps by preventing blocking of the area adjacent to the pump bearing housing, mechanical seal, and coupling and providing easy access to remove the coupling and back-pull-out assembly (including bearing housing and case cover with mechanical seal) for maintenance. This is particularly important for OH2 process pumps with seal reservoirs for Plan 52, 53 and control panels for non-contacting gas seals, along with seal flush plans with coolers such as Plan 23 (FIG. 3). For between bearing pumps, auxiliaries are preferred to be mounted on one side leaving the other side open for easy maintenance.

Definitions, pump pressure ratings.As part of the review process for producing the 12th Edition, Standard Paragraphs—which apply to all rotating equipment—were reviewed. They were compared to the 11th Edition to determine where possible changes in definitions would be required. The definitions needing attention were MAWPand maximum discharge pressure. In both cases, these pressures are now based on maximum specific gravity, and it is the responsibility of the customer to provide this information on the improved format of the API data sheets.

The 11th Edition (as well as all previous API 610 editions) required that OH, BB1 and BB2 pumps be rated for 41 bar (600 psi). The 11th Edition had a special note stating that by the time the 12th Edition is issued, OH, BB1 and BB2 pumps would be required to have a pressure rating equal to that of a PN 40. (300 lb) flange, which is 51 bar (740 psi) at 100°F (38°C). Further discussions revealed that most of these pump sizes generate heads that are relatively low. This translates to the current 41 bar (600 psi) pressure requirement to which most pump manufacturers comply. The final decision was made to revert to the 40 bar (600 psi) rating for these pump types. It should be noted that most manufacturers do have, as an option, higher pressure pump designs, especially for high suction pressure applications which require PN 100. (600 lb), PN 160. (900 lb) and even PN 250. (1500 lb) flanges and heavier wall thickness casing designs.

Explanation has been added to address disassembly after performance testing of BB3 and BB5 pumps to ensure that all water is removed from internal passageways, as water cannot be removed simply by draining for these designs. However, for these multistage pumps, pump disassembly after tests may be invasive to the point of impacting mechanical integrity.

Improved wording and images, diagrams and normative references.One of the main objectives for the API 610 12th Edition task force was to improve wording throughout the document for clarity to assist international users. With this goal in mind, images and diagrams were added to show requirements more explicitly (e.g., baseplate designs), along with expanding the table of contents to include figures and tables, and adding a listing of acronyms and abbreviations

Similarly, a better description of single-stage axial split between bearings BB1 pump classification—foot- or near-centerline-mounted—was added to BB3 and BB4 pumps. “Centerline supported” was added to BB2 pumps. A further clarification was made so that the figures shown generically represent the various pump types and do not reflect actual construction details or certain pump features. This wording was added to help both contractors and end users apply variations of the images without concern. FIG. 6 depicts two additional nozzle orientations for BB1 pumps. FIG. 7 shows a typical top/top nozzle orientation for OH2 single-stage overhung process pumps. This combination was very common in the past, as it provided a cleaner field piping arrangement without typical end suction pump piping obstruction at the ground level, and for modular design systems where space is a premium. These orientations are still purchased today and are not considered as deviations or exceptions to API 610 12th Edition.

Takeaway.This article has touched on the main and other changes from API 610 11th Edition to the 12th Edition. Most of them have impacted pump reliability and maintainability. Changes were made to reflect industry feedback and most end user specification requirements to elevate equipment to a level of minimizing the need of overlay specifications. However, as technology changes and more demanding services arise, the API 610 standard continues to evolve.

Frank Korkowski (korkowskifrancis@gmail.com) is the Manager of Engineered Training at Applied K3nowedge Consulting. He is a consultant recently retired from Flowserve and previously was theMarketingManager for the API 1 and 2 stage process pumps. He spent 45yrin various pump roles with Ingersoll Rand, Ingersoll-Dresser Pumps and Flowserve.Mr. Korkowski earned a BS degree in industrial engineering fromthe New Jersey Institute of Technology,with post-graduate studies in engineering and business administration at Lafayette College and Fairleigh Dickinson University.

Tom Hess (thess@e2g.com) is the Principal Rotating Engineerfor The Equity Engineering Group, Inc. Prior to joining Equity, Mr. Hess worked as aRotatingReliabilityEngineer in an oil refinery.Hehas been fascinated with sealless pumps fornearly30yr. Heearnedhis BSME from Villanova University, is a member of ASME and is a registered professional engineer in the Commonwealth of Pennsylvania. Mr. Hess is a member of the API 685, 610, 682 and 613 Task Forces.

Roger L. Jones (rogerjonessping@aol.com) is a Rotating Equipment Consultant and Task Force Chairmanfor API 610. Mr. Jones spent 32yrin various positions at different Shell companies. In his career,he has held numerous technical and managerial positions in chemical plants and refineries, major capital projects and engineering consulting roles.He earned BS and MS degrees in mechanical engineering from Kansas State University and is a registered professional engineer in Texas. He is the previous chairman of the International Standards Coordinating Committee of the API and head of the U.S. delegation to the various ISO technical committees governing standards for refining and offshore equipment. He is a former member of the International Pump Users Symposium Advisory Committee.

First Introduced in 2000 the API 685 standard describes requirements for sealless centrifugal pumps for petroleum, heavy-duty chemical, and gas industry services. API 685 is the sealless pump equivalent to API 610, which is well known and accepted as industry standard for sealed centrifugal pumps for many years.

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ANSI and API are two process pump styles that are sometimes confused. This uncertainty can lead to users choosing a less expensive ANSI pump when the application demands API (or at the very least, an API pump could do the job more efficiently at a lower operating cost). Less often, a user may choose the more expensive API pump when an ANSI pump could effectively handle the job.

In recent years there has been much discussion on adapting ANSI pumps for expanded use in the oil and gas industry—the domain of the API pump. To meet the environmental demands of the field, the pumps must meet additional standards such as reliability in extreme conditions.

API pumps meet Standard 610 for General Refinery Service as set by the American Petroleum Institute (API). This U.S. trade association for the oil and natural gas industries develops standards for petroleum and petrochemical equipment.

Unlike the ANSI standards, which are dimensional, API Standard 610 centers around the pump’s construction and design, particularly as they pertain to the pump’s ability to handle high temperatures, pressures and emissions.

API pumps are the choice for more aggressive applications in the oil refinery industry. Their casings, bearing houses, mounting feet and back cover arrangement are all designed for maximum efficiency and reliability in oil refinery applications, as well as controlling emissions and safely handling fluids that can cause environmental damage.

In general, ANSI pumps provide reliable service across a range of applications and are the pump of choice for chemical processing. They offer tremendous flexibility and ease of operation. API pumps are heavier duty and should be considered for higher pressure and temperature applications. They are the pump of choice for aggressive oil refinery processes.

For assistance choosing an ANSI or API pump, the experts at C&B are here to help. Let us help you find the best fit for your application.Contact ustoday.