We have just released RODSTAR 2.34 and RODDIAG 1.93. These new versions calculate stress loading for Electra and XD rods differently than previous versions of the software. We have also changed the location of the option to include or exclude buoyancy effects.
On May 6, we received a letter from Arturo Delacruz, Chief Metallurgical Engineer with Weatherford Artificial Lift Systems, requesting us to change the way we calculate the maximum allowable stress calculations for the Electra and XD rods. The text of his letter was as follows:
I request a change of the maximum allowable stress calculations for the EL and XD grade sucker rods to be included on your next upgrade of the RODSTAR Sucker Rod String Design program. As you know, the EL 50,000 psi rating is extremely outdated and the fatigue performance of the EL is not representative of this rating. The original rating did not take into account the minimum stress (Smin) and thus limited the allowable stress range of the EL at higher Smin. This coupled with results of pull-pull fatigue testing and extensive field data led to review and revision of the current rating. The new maximum allowable stress formula for the EL sucker rod is given as follows:
Sa = (55,000 + 0.2143 Smin)SF
Where:
Sa = Max. allowable stress, psi
Smin = Min. stress, psi
SF = Service Factor
Last year we consolidated the EVI Oil Tools Santa Teresa sucker rod plant into our Trico-Greenville plant. In the process, we also consolidated our higher strength rods, the T66 and the XD rods. The XD and the T66 became one single rod with the designation stamped on opposite sides of the wrench square. For this reason, we request to standardize the maximum allowable stress formula for the XD rod to conform to T66/Norris 97 formula. For clarification, the formula is given as follows:
Sa = (T/2.8 +0.375 Smin) SF
Please call if you have any questions and let me know when these changes will be integrated into your sucker rod string design program.
Sincerely,
Arturo Delacruz, Chief Metallurgical Engineer
Weatherford Artificial Lift Systems, Inc
5325 Trico Lane
Greenville, TX 75401
Telephone# (903)455-4441
http://www.weatherford.com
Our policy is to use the stress calculation methods recommended by the sucker rod manufacturers. Therefore, we have made the changes requested by Weatherford and the new versions of the software (RODSTAR 2.34 and RODDIAG 1.93) are now available on our web site. XDIAG will be available shortly.
You can download the new versions of RODSTAR and RODDIAG if your technical support is current. If you are not setup yet to download files from our web page please e-mail us the user name (usually your e-mail address) and the password you want to use and we will set you up to be able to download new releases.