American Petroleum Institute: Standard 682, 4th Edition Shaft Sealing Systems for Centrifugal and Rotary Pumps
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This Fluid Sealing Association Knowledge Series training presentation introduces the American Petroleum Institute: Standard 682, 4th Edition. This is part of a series of presentations of this industry standard. This presentation describes API-682 seal coding system:
Seal Description
Design Options
Seal Size
Seal Support System
▪ This FSA training material is made available for informational purposes only and is made available “AS IS.” It is intended to serve only as a summary of the content of the API-682 standard and not as a substitute for or to replace or supersede the actual language of the API standard.
▪ For the full language of the API-682 standard, please refer to the actual standard and/or refer to API’s website for further information: https://www.api.org/products-and-services/standards. FSA disclaims any and all liability for any injuries or damages to persons or property resulting from reliance upon this informational summary.
Seal Code
API-682 “Annex D”
▪ The mechanical seals code provides a concise way of referring to a design and features commonly supplied with seals
▪ Used with Annex C datasheet to specify purchasing requirements of mechanical seal and sealing systems
▪ Note: Assumes all standard defaults of mechanical seal designs
Seal Code
Seal code has 8 positions broken down into 4 sections
▪ First section has 3 positions describing the seal
▪ Second section has 3 positions describing the design options
▪ Third section has 1 position describing the shaft size in mm
▪ Final section has 1 position describing the seal support plan
Further information on each of these categories can be found in the Fluid Sealing Association’s Knowledgebase.
Seal Code
Section 1 describes the seal
▪ First position designates the seal category (1, 2, or 3). These categories are defined in API-682 section 4.1.2
▪ Second position designates the seal arrangement (1, 2, or 3). These arrangements are defined in section 4.1.4
▪ Third position designates the seal type (A, B, or C). These types are defined in section 4.1.3
Seal Code
Section 2 describes the seal's design options and consists of the 4th thru 6th code positions
▪ Position 4 designates the containment device found on the atmospheric side of the mechanical seal.
▪ Position 5 designates the secondary sealing element material
▪ Position 6 designates the seal face material combination
Position 4 designates the containment device type
P : Plain Gland
L : Floating throttle bushing
F : Fixed throttle bushing
C : Containment seal
S : Segmented Floating throttle bushing
X : Unspecified, for options not covered by the standard options
Seal Code
Position 5 designates the secondary sealing material
F : Fluorocarbon (FKM) elastomer gasket
G : TFE spring energized gasket
H : Nitrile elastomer gasket
I : Perfluorocarbon (FFKM) elastomer gasket
R : Flexible graphite
X : Unspecified, for options not covered by the standard options
Seal Code
Position 6 designates the seal face combination
M : Carbon vs. Nickel Tungsten-Carbide
N : Carbon vs. Silicon-Carbide
O : Silicon-Carbide vs. Nickel Tungsten-Carbide
P : Silicon-Carbide vs. Silicon-Carbide
Q : Silicon-Carbide vs. Silicon-Carbide
R : Carbon vs. Silicon-Carbide
S : Graphite Silicon-Carbide Composite vs. Silicon-Carbide
T : Graphite Silicon-Carbide Composite vs. Silicon-Carbide
X : Unspecified, for options not covered by the standard options
Seal Code
Section 3 describes the shaft size the seal cartridge will be installed on
▪ Section 3 consists of the 7th position of the seal code
▪ Shaft size is expressed millimeters
▪ Shaft size is rounded up and expressed in 3 digits
25 mm = 025
37.25 mm = 038
Seal Code
Section 4 describes the seal support systems
▪ Section 4 consists of the 8th position and describes the seal support piping plans that will be used on the seal installation.
▪ Piping plan descriptions are found in Annex G
▪ If more than 1 piping plan is used, the piping plans are listed with a forward slash "/" between them
▪ E.g.: A seal utilizing a plan 11 and a plan 53B is denoted as "11/53B"
Further Information
American Petroleum Institute Standard 682
For further information and detail please review the API 682 standards document.
Request a copy of the “API Std 682” from the API Publication
