AS-BJ70 Welded Metal Bellow Seal To Replace Johncrane 670 Seal

AS-BJ70 welded metal bellow seal is to replace Johncrane 670 seal. It is all-Alloy C-276 Shaft Seal for Highly Corrosive Fluids and for refinery low-temperature services. Other common applications include caustics, acids, amines and products with H2S, such as sour water and sour hydrocarbons.

Operating Limits:
Temperature Limits: -100°F to 550°F/-75°C to 290°C (depending on material being used)
Pressure Limits: Vacuum to 360 psi(g)/25 bar(g)
Speed Limits: 5000fpm/25m/s

Features:
Available in single or double cartridge arrangements, or can be shaft mounted; made with a 45-degree tilt edge at the bellows' inside diameter to make stresses evenly distributed.
In dual seal arrangements a non-pressurized buffer or pressurized barrier fluid can be adoptd. A pumping ring recirculates barrier fluid, assuring cooler operating temperatures and longer-time reliable performance.
Superior nesting ripple plate shape with a three-sweep radius which design permits the bellows seal device to be flexed repeatedly.
Self-cleaning design permits no need for external flushing, filters or cyclone separators.

About Us：

Background Knowledge：

Reasons and improvement measures for the leakage of the mechanical seal of the axis flow pump
1. Equipment status
A petrochemical company polypropylene 2PP device pre -polymerization reactor R2200 is a small single -ring tube reactor. Its axial flow pump mechanical seal uses double mechanical sea and API Plan 53C/32 flushing scheme.

2. Mechanical seal failure and disrepair
Recently, the two mechanical seal failures have been manifested as compressing pistons vancarin's leakage. The disintegration finds that the atmospheric side wear is much more severe than the medium side wear. From the perspective of two atmospheric side friction, poor lubrication or excessive friction pairs pressure is the main cause of mechanical seal failure.

3. Cause investigation
<1) Process operation parameters. The operating parameters of the R2200 are normal, and the temperature TE9201 maintains 18 degrees Celsius. Pressure PT9201 maintains 3.48MPa, no super mild & super -cricket phenomena: 32 Scheme Rinse acrylic flow FIC9201 is maintained at 400kg/h. The temperature is 45 degrees Celsius, without abnormal interruption and ultra -temperature phenomenon. Due to the serious oil leakage, the operator operates Z2200 each time.

If you inquire the Z2200 Pistons, LSLL9802 has no alarm process, which proves that the 53C scheme has no over -pressure phenomenon. The sealing oil cooler has good circulation, so the possibility of poor lubrication can be excluded.

<2) Check the parts. Carefully check the disintegration parts. The appearance of the O rings is intact, and no obvious abnormalities and damage are seen: check the sleeve and find that the positioning hole on the shaft sleeve deformation is oval. The maximum volume of the shaft movement is 0.7mm.

<3) Mechanical seal’s PV value analysis
PV = 16. 17MPa. The mechanical seal friction pair material is carbon graphite vs Calcium carbide. The allowable PV value of this friction pair is 12.25~15.OO MPa • m/s. Obviously, without deformation of the positioning hole, the PV value exceeds the allowable range. Due to the deformation of the positioning hole and the movement of the shaft sleeve, the PV value is even greater by 0.58MPa·m/s, resulting in serious friction in the friction pair of the mechanical seal, and local overheating may occur, causing wear of the carbon graphite rotary face of the mechanical seal on the atmospheric side and multiple abnormal leaks of the machine pump & its shutdown for maintenance.

4.Improvements
<1) Improvement of shaft sleeve. In response to the problem of deformation of the positioning hole of the shaft sleeve, two plans were proposed on site: one was to enlarge other holes according to the deformed punching size of the positioning hole, and at the same time, the driving ring was expanded to attack the line. The second is to keep the original positioning holes and process additional threaded holes in the drive ring, which are only used to position the bushing of the mechanical seal. Considering factors such as machining accuracy, the second plan was adopted.

<2) Optimize the amount of compression. Through the above calculation and analysis, it is necessary to optimize the atmospheric side end face specific pressure so that the PV value is within the allowable range. In this regard, many checks and comparisons were made in terms of changing the end face size and compression amount of the rotary face of the mechanical seal, and finally it was decided to keep the size of the original rotary face unchanged and only optimize the compression amount. After calculation, the compression amount is reduced and the PV value is maintained at 14.6MPa.m/s to ensure that it is within the allowable range for the mechanical seal.

The compression amount was optimized on site by cutting the back of the atmospheric side rotary face of the mechanical seal thinly. The optimized mechanical seal has been used continuously for two years. The decrease of the pressurized piston scale is 0.8-1mm/h, and the leakage of the mechanical seal is 0.6 drops/min, which meets the production requirements of the mechanical seal device.