2400 Longhorn Industrial Drive, New Braunfels, Texas 78130Ph: (830)629-8080 Fax: (830)629-6899 email: info@myej.net

Copyright © 2001 Senior Flexonics Pathway.

NEWS RELEASE

When Toyo En-gineering was re-quested to sup-ply replacementexpansion jointsfor a Kyushu OilLtd. FCC, It wasclear to everyonethat the very bestt e c h n o l o g ywould be neces-sary. The cus-tomer had expe-rienced crackingproblems on cer-tain high tem-perature FCCexpansion jointsand was verysensitive aboutthe life span of expansion joints in FCC service. SeniorFlexonics Pathway employed the most current technol-ogy available to insure the best performance for KyushuOil Ltd.

The double gimbal expansion FCC flue gas expansionjoint was designed to handle 57 PSIG (4.01 Kg/cm2) ata temperature of 14270F (775 C). The expansion jointwas of hot shell design. In order to eliminate problemswith cracking of the pipe in service, the pressure thrustrestraint rings attached to the hinge arms were designedto be floating structures. This floating ring concept al-lows the pipe to grow radially without being restricted bythe cooler rings. In the creep range of operating tem-peratures, this feature is critical to avoid excessive pipestress.

Stainless steel is subject to embrittlement after manyyears of service in the creep range. This problem is mini-mized by careful control of the ferrites in the depositedmetal of pipe welds and by eliminating welds whereverpossible. To minimize welds, Senior Flexonics Pathway

TOYO ENGINEERING DEMANDS THE BEST FCC EXPANSION JOINT

used proprietary pipe expander equipment to create thefour transitions required for the double gimbal design.This process eliminated 8 circumferential welds that oth-erwise would be required. Senior Flexonics Pathway alsocontrolled the ferrite level of the weld wire and then solu-tion annealed the pipe to put the pipe into the most sat-isfactory condition for long term use at high tempera-ture.

Most Senior Flexonics Pathway customers consider ahigh nickel alloy like Alloy 625 to be the best expansionjoint material for FCC service. However, FCC operatingconditions are above the safe operating temperature formost high nickel alloys including Alloy 625. To keep thebellows in the best operating temperature range, SeniorFlexonics Pathway internally insulated the bellows. Aspecial type of high nickel alloy called Alloy 625 LCFwas used for the bellows. Alloy 625 LCF is marketedexclusively by INCO Alloys. This very fine grain versionof Alloy 625 has superior fatigue performance and resis-tance to embrittlement up to 1200OF (648 C), signifi-cantly higher than straight grade Alloy 625. To insure thevery best fatigue performance, the bellows were not an-nealed after forming.

Each bellows was of ply testable construction. This con-cept involves a two ply bellows in which each ply is de-signed for the full operating conditions. This results in a100% safety factor on the bellows elements and the ability

NR 73

Technology for Kyushu Oil Refinery Ltd.

to safely operate the expansion joint even if a leak oc-curs on the inner ply of the bellows. A Senior FlexonicsPathway patented Red Top leak detector system wasinstalled on the ply testable pressure tap on the outerply. The Red Top leak detector system has a highly vis-ible red post that pops up if any leakage is detected inthe inner ply of the bellows element.

With insulation inside the bellows, it is possible to havethe bellows drop below the condensation point of acidsin the media in severe weather conditions. To stabilizethe bellows operating temperature and maintain a highenough temperature to avoid condensation that couldcorrode the bellows, external insulation was factory in-stalled on the outside of the bellows elements.

Senior Flexonics Pathway also installed thermocoupleson each bellows in the double gimbal to provide a methodof monitoring the bellows skin temperature in service.The ideal temperature range is between 400OF (204OC)and 1000OF (538OC). By monitoring the bellows in ser-vice with thermocouples, operators can document thatthe bellows are operating in a temperature range thatwill result in the best long term performance of the ex-pansion joint.

To find out more about expansion joints for FCC service,contact Senior Flexonics Pathway.

(Continued)

Illustration showing floating rings,telescoping liners and insulation usedto stabilize the bellows temperaturein service.

Illustration showing the method used toattach thermocouples to the bellows forcontinuous monitoring of the bellowsoperating temperature.

Illustration showing method of attachment of Senior Flexonics Pathway patented Red Top leak detection monitor on the ply testablebellows. The bleed valve allows the escape of pressure that may build up between the plies during inital operation.