ROHRBACK COSASCO SYSTEMS TEST REPORT

Transcription

1 ROHRBACK COSASCO SYSTEMS TEST REPORT Subject: RSL Retriever 2500 psi Debris Test Report Issued By: Rohrback Cosasco Systems, Santa Fe Springs, CA USA Date: June 6, Website:

2 Management Summary This report summarizes the results of the testing of the additions of wipers and new drive pin to the COSASCO RSL/HRSL Retriever. Teflon Wipers (Disc and Rings) and a new sized Drive Pin have been added to the RSL/HRSL Assembly to further improve the resistance of debris accumulation in the head of the retriever. The COSASCO RSL Retriever is one of the safest, most reliable, and convenient retrieval tools for the installation and retrieval of corrosion coupons and probes from a two-inch access fitting while pipeline or vessel is under pressure. Its non-telescoping, compact design enables the user to access bottom-of-theline monitoring locations where access area is usually minimal, avoiding the need to produce access pits or to raise pipe work. Used in conjunction with a COSASCO Service Valve, system pressure is safely ported into the tool which allows the valve to be opened and the retrieval operation to be performed. Rotation and translation in and out of the fitting is controlled by two adjustable handles. The major components of the RSL/HRSL Retriever are: a head assembly, rotation tube, translation tube, and socket adapter assembly. Sealing within the unit is achieved with Viton o-rings and graphite-impregnated Teflon dynamic seals. The addition of the Teflon Wipers and Drive Pin will further enhance the RSL's field proven performance and improve operability on bottom-of-the-line retrievals where debris accumulation is most prominent. Page 2 of 16

3 Contents 1 Objective 2 General Description 3 Procedure/Methodology 4 Visual Examination & Findings 5 Conclusion Page 3 of 16

4 1 OBJECTIVE The purpose of this test was to examine the effects of debris inside the RSL retriever while operating the tool under pressure. 2 GENERAL DESCRIPTION The test was conducted on both the current retriever and the current retriever with the addition of Teflon wipers on the head assembly end of the retriever. In this case we used an equal mixture or two different types of sand particles: fine grained sand (used for sandblasting) and coarse grained sand (beach type sand). RSL Retriever Spare Seals for Head Assembly (If Necessary) Teflon Wipers (3 sets) Retriever Used Model: COSASCO RSL Pressure Rating: 2500 PSI (17.2 MPa) Temperature Rating: 15 F F (-26 C -204 C) Stroke Length: 18 Inches Page 4 of 16

5 Two Sand Types Fine Grained Sand (Used for Sandblasting) Coarse Grained Sand (Beach Type Sand) Teflon Wipers (3 Used per Retriever) Inside Rotation Tube Between the Rotation and Translation Tube Between the Translation Tube and Outer Barrel Page 5 of 16

6 3 PROCEDURE/METHODOLOGY The retriever was hydrotested first at nearly 3,000 psi which is the maximum pressure rating of the currently installed gauge to insure that it was operating properly. The hydrotest setup is shown below (the picture on the right illustrates the pressure at nearly 3,000 psi). 3,000 PSI Reading Next we began performing the plug retrievals. The tests were all carried out in the bottom line position to maximize debris accumulation inside the retriever. Access Fitting Test Rig Setup RSL Retriever Valve Page 6 of 16

7 Retrieval Testing Procedure Note: Steps 1-6 were performed without Teflon wipers. 1. Our first plug retrieval was performed without debris (sand) at about 1,600 psi. The pull proved to be acceptable. The plug was installed back into the access fitting and the testing continued. 2. Next, we poured 5 ounces of the mixed dry sand directly into the retriever and proceeded with the plug retrieval at about 1,300 psi (due to pressure drop from previous pull). There was clear indication of grinding within the retriever, but the resistance was mild to moderate. Grinding was apparent during plug removal from access fitting and plug translation down into the retriever towards the head assembly. The plug was then returned to the access fitting. The retriever was removed from the valve in preparation for the next step. 3. We proceeded to pour 5 more ounces of the debris mixture directly into the retriever, bringing the debris content to a total of 10 ounces. The retriever was then reattached to the valve for plug retrieval from the access fitting. Considerable grinding and skipping occurred during this entire operation, presumably from the larger particles of debris. There were some issues getting the socket adaptor to engage into the pilot thread on the plug. The debris was making it difficult to determine whether proper engagement was achieved to proceed with the pull. Eventually we gained confidence that the adaptor was threaded into the plug pilot thread and continued with the pull. During operation, the tool would occasionally get jammed up and skip during rotation while attempting to unscrew the plug from the access fitting. It was unclear at this point whether this was due to debris getting caught between the plug and access fitting threads, debris rubbing within the mechanics of the tool, or a combination of both. Hard grinding was present during rotation and translation of the plug. Either way, with a significant degree of difficulty, we proceeded with the pull successfully. 4. The retriever was then removed from the valve and the plug was examined: While on the retriever stand, there was considerable resistance from grinding during translation of the plug. This was evidence of debris particles interfering with the revolution of the translation tube. There were no major indications of thread damage on the plug from the experiment. The plug was reinserted into the access fitting for the next retrieval test. 5. The retriever was transported into the lab and disassembled for examination. See the following section Visual Examination & Findings for results. Page 7 of 16

8 6. After photographs were taken and results documented from the first test (without Teflon wipers) the retriever was cleaned of all possible debris and re-lubricated. 7. Next, the Teflon wipers were placed onto the tool as shown: Teflon Wipers 8. Once the retriever was fully assembled with all three Teflon wipers and transported back to the test rig, we preceded to add 10 full ounces of the mixed dry sand directly into the retriever. The retriever was then reattached to the valve (same bottom line used for all previous steps) for plug retrieval from the access fitting at about 1,500 psi. The indication of grinding was much more prevalent throughout this operation requiring significantly more torque to operate the tool against the increased resistance. This is to be expected since the retriever was filled with 10 ounces (dry) all at once, and one would anticipate that the previous test caused considerable permanent damage to various parts of the retriever. Extensive grinding and skipping occurred during the retrieval and insertion process, at one point the tool appeared to cease, presumably from the larger particles of debris. But the plug was returned successfully. Page 8 of 16

9 9. The retriever was once again removed from the valve and taken into the lab for dismantling and inspection. Additional Notes: The pressure gauge was not functioning properly with debris introduced into the system. It was evident that the pressure gauge had a significant delay on detecting a pressure during the tool equalization process. The head assembly did not exhibit notable signs of grinding or skipping when removed from the retriever body and rotated separately. Page 9 of 16

10 4 VISUAL EXAMINATION & FINDINGS The following photos were taken after the first debris test, without the Teflon wipers. Internal Assembly (Valve Connection End) Translation - Rotation Tube Assembly Head Assembly Outer Barrel (Head Assembly End) Page 10 of 16

11 Socket Adapter Carrier The following photos were taken after the second debris test, with Teflon wipers. Translation - Rotation Tube (Head Assembly End) Teflon Wiper Removed Packed Sand From Inside Translation Page 11 of 16

12 Rotation Tube (Wipers Removed) Head Assembly Page 12 of 16

13 The following photos were taken after the all testing was completed, and all parts cleaned from debris to expose bare surfaces. Rotation Tube (Head Assembly End) Evidence of Severe Scoring (Valve Connection End) Page 13 of 16

14 Evidence of Severe Scoring Socket Adapter Carrier Outer Barrel Pressure Gauge Hole (Packed with Debris) Evidence of Severe Scoring (Valve Connection End) Page 14 of 16

15 Drive Pin (Tested) Drive Pin Comparison Evidence of Severe Scoring Teflon Wipers Page 15 of 16

16 5 CONCLUSION Despite the harsh debris conditions applied the RSL retriever was still able to perform its function, with and without the Teflon wipers. Although the degree of difficulty in using the tool did increase significantly. It was particularly difficult to determine engagement into the plug pilot threads, and there was a great amount of torque required to unfasten the plug from the access fitting. The only sections of the retriever that exhibited notable to severe damage from the debris were the areas of tighter running clearances within the barrel assembly. When the head assembly was dismantled, cleaned, and inspected, there was no visible damage to any of the head parts from testing. As stated earlier in this report, the head assembly did not exhibit signs of grinding or skipping when removed from the retriever outer barrel and rotated separately. None of the seals on the RSL retriever required replaced throughout the course of this experiment given that there were no signs of water leakage while operating under pressure. Since the retriever did not fail during the test (meaning that the retriever did not cease) and the head assembly was not noticeably damaged at any point within the experiment, it was not possible to determine the overall effectiveness of the Teflon wipers on the head seals. However, it was observed that the wipers are very effective on prevented debris from reaching the head assembly as illustrated in the following photographs. New Untested Head After Test (No Wipers) After Test (With Wipers) Page 16 of 16