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Question
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Answer
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| 1. What is Lokring? | Answer: Lokring fittings use a patented, elastic strain pre-load technology to connect small diameter piping and tubing without threading or welding. Lokring fittings are designed for use in field fabrication, for rapid repair, for installation in tight access areas, and for ties-ins of shop fabricated piping and tubing. The installation of Lokring fittings is simple, extremely repeatable and can be made in a fraction of the time required to weld the connection. |
| 2. How does Lokring work and why? | Answer: During installation, the pipe wall is radial compressed first elastically and then plastically by the swaging action of the fitting. This swaging action creates residual compressive stresses circumferentially in the inside diameter of the pipe under the sealing lands of the fitting body and corresponding tensile stresses in the fitting drive rings. These stresses remain balanced throughout the pressure and temperature changes within the operating parameters of the fitting. |
| 3. How is Lokring installed? | Answer: Fittings are installed using a unique LokTool® Installation Unit and a hydraulic pump (manual, electric or air driven). |
| 4. What is the difference between Lokring and welding? | Answer: Lokring fittings give you the performance of a welded joint without the hotwork. Lokring fittings are installed hydraulically and welding requires the infusion of heat. |
| 5. How is Lokring superior to Hot Welding? | Answer: Lokring fittings can be installed without hotwork. This allows fittings to be installed in areas where solvents and other chemicals may be present. In addition Lokring fittings can significantly reduce the cost of installing pipe in the field. Depending on the quality of the weld. Lokring may offer several advantages over its welded counterpart. Lokring fittings offer “no heat effected zone” which in a weld is susceptible to accelerated corrosion. In addition Lokring will eliminate weld slag, incomplete fusion, weld suckback, the need for passivation and x-ray. Some of the other advantages are as follows: Schedule improvements, Elimination of hot boxes, establishing fire watches, and the need for highly skilled welders which can be used in other areas such as structural steel, boiler work and high alloy steels. |
| 6. What piping can Lokring be used on? |
Answer:
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| 7. What materials are in the Lokring fittings? | Answer: The entire stainless steel fitting (coupling body and swaging rings) is manufactured from ASTM A276 or A479 Type 316/316L (UNS S31603) dual-certified austenitic stainless steel. Our Carbon steel products are made from special, high-strength, micro-alloyed carbon steel bar or drawnover- mandrel, stress relieved tubing. Bar stock conforms to ASTM A675 and tubing conforms to ASTM A513 / Din 2393, grade ST 52.3. 90/10 Copper Nickel product is made per MIL-T-16420. |
| 8. Can Lokring fittings be used to connect different metals such as SS and CS? | Answer:
The use of Lokring carbon steel product to connect stainless steel pipe
is not suggested. However, Lokring stainless steel fittings can be used
to connect carbon steel pipe within the pressure temperature limitations
as defined by the SS fitting. See your Lokring Brochure for material-specific Pressure-Temperature Ratings. |
| 9.
Does the system need to be “hydroed” after a Lokring installation? (NOTE: “Hydroed” refers to hydrostatic testing with liquid (typically water) at 1.5 x the rated design pressure). |
Answer: After a Lokring installation fittings/piping, the systems must be inspected per ASME standards. The standards are located in Chapter VI Examination, Inspection and Testing. The tests for B31.1 and B31.3 vary. These standards may require various tests, some of which are as follows:
A hydro test specifically calls for water or a specified fluid or test medium. In some cases due to the piping service, it may not be advisable to introduce water into the system. |
| 10. Does a Lokring installation need to be x-rayed? | Answer: Lokring fittings do not need to be x-rayed after installation. The install and inspect marks assure proper fitting installation. |
| 11. If my specs require the welds to be X-rayed, how about Lokring welded fittings? |
Answer:
In order to provide the best possible product for customer applications
Lokring manufactures “shapes” such as elbows tees and flanges
in a modular fashion by welding our proprietary ends to commercially
available and approved components. Visual examination of these welded
fittings is NOTE: Chapter VI in ASME B31.3, Examination, Inspection and Testing requires visual examination of welds and 5% spot Radiography. The requirement for spot radiography can be replaced with documented in process examination in accordance with paragraph 344.7. Chapter VI in ASME B31.1, Examination, Inspection and Testing allows for visual examination of welds only, for applications under 750° F and wall thickness below ¾” in thickness. If a customer has an application with Stainless Steel fittings for use in a temperature range above 750° F, they should specify our SS-3300 line of fittings that do undergo 100% radiographic examination |
| 12. Does the pipe need to be sanded to the metal level if it has paint on it? | Answer: Although the Lokring fitting will “bite” through the paint. If the pipe is not sanded to bare metal, it can not be visually inspected prior to installation. |
| 13. Can you use a pipe mule to cut the pipe like it is done for a weld? | Answer: When a pipe mule is used to hold the pipe, care must be taken not to grasp the pipe within 1.5 pipe diameters of the ends. This will ensure that the pipe does not have bite marks under the Lokring sealing lands. |
| 14. Can I use a grinder or a disc grinder to prepare the pipe end? | Answer: Do not use a grinder or sanding disc to prepare pipe for Lokring installation. The use of a grinder or disc sander may leave uneven or flat spots on the pipe. This is unacceptable for Lokring prep. |
| 15. What happens if there is “daylight” showing when the pipe should be bottomed out in the gauge tool? | Answer: When daylight is showing in the gauge tool, it indicates that the pipe ends have not been cut square or within the 5 degrees of square required for a proper Lokring installation. |
| 16. What happens if the pipe falls through the NOGO slot in the gauge tool? | Answer: This indicates that the pipe does not meet typical size requirements. The pipe is either undersized or oval. |
| 17. What happens if the pipe does not fit in the GO in the gauge tool? | Answer: This indicates that the pipe does not meet typical size requirements. The pipe is either oversized or oval. |
| 18. What happens if the fitting is complete and the entire “inspect” oval is showing? | Answer: If the entire inspect oval is visible this indicates an improper installation and the fitting must be removed or backwelded. |
| 19. Can there be a gap inside the fitting between the ends of the pipes (or between the pipe end and the stop)? | Answer: Yes, it is not necessary for pipe ends to be flush. The Lokring install and inspect marks help to verify the proper installation. |
| 20. What if the outside of the pipe is pitted? | Answer: Obviously without seeing the exact condition this would not be appropriate to answer. However, if the pipe / tubing is within specification (outside diameter), and the surface cannot be prepped to proper standards, then the use of an anaerobic sealant such as Loctite PST may be used to assist in the sealing. Due to the many variables involved, adequate performance of the assembly cannot be guaranteed by Lokring. |
| 21. How do you know the Lokring fitting installation is good? | Answer: Once the fitting has been installed you can visually verify that the pipe is located in the correct position within the fitting by viewing the Install and Inspect marks. The purpose of the install and inspect ovals are to establish the correct positioning of the pipe within the fitting. To verify a good installation, after appropriate pipe prep, after LOK’ing the fitting you should see the full install mark and a partial inspect mark, the fitting body protruding from underneath the driver and the driver brought up to the fitting body with no more than a small gap between them. |
| 22. What tools are needed to do ¼” to 3” fittings? | Answer: Tool kit selection can be tailored to customer requirements depending on fitting sizes being installed. Refer to the Tool Matrix found in the Distributor Training Manual. |
| 23. Can we use our own 10,000 psi Enerpac or do we need to use Lokring’s? | Answer: Any standard pump may be used as long as it meets Lokring’s requirements for installation. Lokring requires certain standards for safety. This includes certain overpressure requirements for hoses and quick disconnects. (Consult Lokring for its recommendations). Under no circumstances should a pump, rated for pressure higher than 10,000 psi, ever be used in conjunction with Lokring tooling. |
| 24. How often do the tools need to be serviced? | Answer: Tools should be maintained on a regular basis. This regular servicing requires lubrication. Proper tension on the shoulder bolt and visual examination of all inserts and moving parts. Proper maintenance of the tools will allow for years of performance. If major repair or servicing is required consult you regional Lokring distributor or contact Lokring direct. |
| 25. Why do you have to “cycle” a hydraulic tool? | Answer: In order to verify the proper function of the hydraulic tooling, the equipment should be cycled once; this assures that the tool moves smoothly and that there is sufficient hydraulic fluid in the pump to complete the installation. |
| 26. How much room is needed for the tooling? | Answer: Reference LP-105 Installation procedure |
| 27. Can you re-use a fitting? Why not? | Answer: Lokring fittings are permanent. Once they have been installed they can not be reused. Lokring does have a make-n-break design if this is something your system needs. |
| 28. What if it leaks? |
Answer: Lokring’s patented design assures a significant reduction in leakage when compared to welded joints (virtually nil). However, if necessary, a Lokring fitting can be cut out and replaced. With our patented design, slip-fitting another fitting of longer length or installing a “T” is no problem. In addition, Lokring fittings can be back welded. Consult Lokring for specific back welding procedures. (NOTE: There is a specific MAS repair fitting that can be found in the drawing section of the binder). |
| 29. I “guess” they will work OK in utilities, but I’m not so sure about process streams…. | Answer: Lokring fittings offer the performance of a welded joint. To date, the bulk of Lokring applications have been on process fluids such as solvents and gases. If an application is unknown, fill our and forward an Applications Data Form and have the factory review your requirements. |
| 30. Are you supposed to allow for system expansion similar to socket welding? |
Answer: This is not necessary. Lokring fittings are installed and hanging requirements are the same as a welded system. Lokring does not require the back-off requirements of a socket welding. Because of the lack of need to leave space, Lokring design has superior flow path characteristics and still meets all hanging requirements similar to welding. NOTE: Competitors
don’t always meet the hanging |
| 31. Show me where LOKRING is accepted and code qualified. |
Answer:
“ASME does not ‘approve’, ‘rate’ or ‘endorse’
any item, construction, proprietary device or activity.” This information
can be found on the back of the title page of the B31.1 and B31.3 codes
However, ASTM B31 does provide for reference, nominal guidelines and
requirements for the owner, designer, manufacturer and constructor to
qualify materials and piping product forms, whether proprietary or not.
Under the B31 codes, the Lokring fitting would be considered a “proprietary”
mechanically attached coupling. To meet the intent of the B31 codes,
Lokring,
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| 32. What temperature and pressure will it withstand? | Answer:
See your Lokring Brochure for material-specific, size specific Pressure-Temperature
Ratings and your Binder under the specific product line’s general
information section. Typically, Carbon Steel is rated from -20° F
to 650° F, Stainless Steel from -60° F to 800° F, 90/10 Copper
Nickel from -60° F to 425° F, 70/30 Copper Nickel from -60°
F to 425° F and stainless tube fittings from -60° F to 800°
F. Pressures rating vary with size. |
| 33. Will it work on steam and steam condensate? Dowtherm? | Answer: Lokring fittings can be used on steam and condensate up to the temperature rating of the fitting. Lokring does not suggest use on superheated steam applications. Dowtherm (heat transfer oils) are acceptable through the rating of the fitting; however, at this time, Lokring does not suggest the use on Dowtherm/Syltherm vapor applications. |
| 34. Can you make … ? | Answer: Because of our modular method of construction, Lokring can manufacture most piping configurations. Please consult with Lokring on special requirements. |
| 35. Metric sizes? | Answer: At this time, Lokring offers only limited metric sizes. See your Regional Salesman for specific applications. Please consult Lokring for specific applications. |
| 36. In regards to wall thickness, what is too thin (considering internal corrosion)? | Answer: We should not try to answer a question about specific end usage; internal corrosion is the user’s judgment. Most products can be typically used on schedule 10 through schedule 80 (MAS is not accepted on schedule 10, but may work in certain applications). |
| 37. Can you remove the fitting after installation? Do you make separable fittings? | Answer: Lokring fittings are equivalent to a weld in many ways. As is true for a weld, the Lokring offers a tamper-proof LOK that cannot be removed once installed. Lokring does provide a separable solution in our face seal o-ring fitting. |
| 38. What if the swage rings come off prior to installation? | Answer: The fitting can either be returned to Lokring or the swage ring lightly tapped back in place. Swage rings are preinstalled at the factory to simplify the installation, this preinstall is a light press fit that can result in rings dislodging if the fitting is handled roughly. The swage ring may be reinstalled and the installation completed. |
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39. How close can I weld/braze to a LOKRING fitting?
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Answer: Prior to installation, welding can be performed within 1 pipe diameter of the joint. To prevent the ESP technology from compromise after the fitting has been LOK’ed, welding should not be performed within close proximity of a Lokring fitting (an exact distance cannot be established due to large process variations). It is important to minimize any differential heating of the fitting – pipe interface.
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