Pipe sealing compound/adjunct lubricant

Abstract

The present invention describes a pipe sealing compound/adjunct lubricant used to prevent gas or liquid leaks when applied to pipe threads and other connections of the same. The compound relies on silicone oil lubricant(s) and one or more friction modifier(s), viscosity builder(s) and filler material(s). The compound contains a viscoelastic liquid that does not have a curing phase and is resistant to hardening and/or drying. The compound is chemically resistant to a wide variety of liquids and gases, is food safe and can withstand extreme high or low temperatures and precipitous temperature fluctuations. The compound has been found to exhibit an inverse pressure to leak rate phenomena.

Claims

1. A viscoelastic non-curing liquid sealing composition comprising silicone oil, and a building block, wherein the building block comprises a fine to ultra-fine polytetrafluoroethylene (PTFE) fumed silica and fine to ultra-fine inorganic powders of calcium carbonate, wherein silicone oil is present at 50% to about 90% wt/wt of the composition, the PTFE is present in the range of about 2% to about 20% PTFE wt/wt of the composition, the fumed silica is present in the range of about 0.5% to about 10% wt/wt of the composition, and the fine to ultra-fine inorganic powders of calcium carbonate are present in the range of about 8% to about 10% wt/wt of the composition, and wherein said composition exhibits a viscosity in the range of about 2×10.sup.4 cSt to about 5×10.sup.5 cSt at 25° C., and wherein said composition exhibits an inverse pressure to leak rate phenomena.

2. The viscoelastic non-curing liquid sealing composition of claim 1, wherein the inverse pressure leak rate phenomenon is determined by helium leak detection, and wherein when the leak rate starts out in the range of about 10.sup.−9 atm cc/sec then, as the pressure increases, the leak rate slows to an order of magnitude of about 10.sup.−10 atm cc/sec.

3. The viscoelastic non-curing liquid sealing composition of claim 1, wherein the silicone oil is present in the range of about 79% to about 85% wt/wt of the composition.

4. The viscoelastic non-curing liquid sealing composition of claim 1, wherein the PTFE is ultra-fine.

5. The viscoelastic non-curing liquid sealing composition of claim 4, wherein the PTFE is present in the range of about 5% to about 10% PTFE wt/wt of the composition.

6. The viscoelastic non-curing liquid sealing composition of claim 1, wherein the fumed silica is present between about 3% to 5% wt/wt of the composition.

7. The viscoelastic non-curing liquid sealing composition of claim 6, wherein the fumed silica is present at about 3% wt/wt of the composition.

8. The viscoelastic non-curing liquid sealing composition of claim 1, wherein the calcium carbonate is a fine powder.

9. The viscoelastic non-curing liquid sealing composition of claim 1, wherein silicone oil is present at about 90% wt/wt of the composition, the PTFE is present at about 7% wt/wt of the composition, the fumed silica is present at about 4% wt/wt of the composition, and the fine to ultra-fine inorganic powders of calcium carbonate are present at about 8% wt/wt of the composition.

10. A viscoelastic liquid non-cure sealing composition comprising silicone oil, fine to ultra-fine polytetrafluoroethylene (PTFE), and fine to ultra-fine inorganic powders of calcium carbonate fumed silica, wherein silicone oil is present at 50% to about 90% wt/wt of the composition, the PTFE is present in the range of about 2% to about 20% PTFE wt/wt of the composition, the fumed silica is present in the range of about 0.5% to about 10% wt/wt of the composition and the fine to ultra-fine inorganic powders of calcium carbonate are present in the range of about 8% to no more than about 10% wt/wt of the composition, wherein said composition exhibits an inverse pressure to leak rate phenomena, wherein the inverse pressure leak rate phenomenon is determined by helium leak detection, and wherein when the leak rate starts out in the range of about 10.sup.−9 atm cc/sec then, as the pressure increases, the leak rate slows to an order of magnitude of about 10.sup.−10 atm cc/sec.

11. The viscoelastic liquid non-cure sealing composition of claim 10, wherein said composition exhibits a viscosity in the range of about 6.4×10.sup.4 cSt to about 9.9×10.sup.4 cSt at 25° C.

12. The viscoelastic liquid non-cure sealing composition of claim 10, wherein the silicone oil is present in the range of about 79% to about 85% wt/wt of the composition.

13. The viscoelastic liquid non-cure sealing composition of claim 10, wherein the PTFE is present in the range of about 5% to about 10% wt/wt of the composition.

14. The viscoelastic liquid non-cure sealing composition of claim 10, wherein the fumed silica is present at about 3% wt/wt of the composition.

15. A method of sealing threaded piping and/or plumbing fitting comprising: a) applying the viscoelastic liquid sealing composition of claim 1 to male and/or female threads contained in said piping or plumbing fitting; and b) connecting said composition applied threaded piping and/or plumbing fitting to a separate threaded piping and/or plumbing fitting, wherein said composition exhibits an inverse pressure to leak rate phenomena.

16. The method of claim 15, wherein the inverse pressure leak rate phenomenon is determined by helium leak detection, wherein when the leak rate starts out in the range of about 10.sup.−9 atm cc/sec then, as the pressure increases, the leak rate slows to an order of magnitude of about 10.sup.−10 atm cc/sec.

17. The method of claim 15, wherein the silicone oil is present at about 90% wt/wt of the composition, the PTFE is present in the range of about 5% to about 10% PTFE wt/wt of the composition, and the fine to ultra-fine inorganic powders of calcium carbonate is present in about 8%.

18. The method of claim 16, wherein the threaded piping and or plumbing fitting is selected from the group consisting of adaptors, elbows, couplings, unions, nipples, reducers, double-tapped bushings, tees, double-tees, crosses, caps, plugs, barbs, valves, compression fittings, flair fittings, flange fittings and combinations thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) Before the present compositions, methods, and methodologies are described, it is to be understood that this invention is not limited to particular compositions, methods, and experimental conditions described, as such compositions, methods, and conditions may vary. It is also to be understood that the terminology used herein is for purposes of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only in the appended claims.

(2) As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Thus, for example, references to “a pipe fitting” includes one or more pipe fittings, and/or compositions of the type described herein which will become apparent to those persons skilled in the art upon reading this disclosure and so forth.

(3) Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention, as it will be understood that modifications and variations are encompassed within the spirit and scope of the instant disclosure.

(4) As used herein, “about,” “approximately,” “substantially” and “significantly” will be understood by a person of ordinary skill in the art and will vary in some extent depending on the context in which they are used. If there are uses of the term which are not clear to persons of ordinary skill in the art given the context in which it is used, “about” and “approximately” will mean plus or minus <10% of a particular term and “substantially” and “significantly” will mean plus or minus >10% of the particular term. In embodiments, composition may “contain,” “comprise” or “consist essentially of” a particular component or group of components, where the skilled artisan would understand the latter to mean the scope of the claim is limited to the specified materials or steps “and those that do not materially affect the basic and novel characteristic(s)” of the claimed invention.

(5) As used herein, “silicone oil” means any liquid polymerized siloxane with organic side chains.

(6) As used herein, “builder,” including grammatical variations thereof, means a substance added to a material as a filler.

(7) As used herein, “filler” or “bulking agent” means particles added to binders (plastics, composites, concrete) that can improve specific properties.

(8) As used herein, “viscosity booster” means a substance added to a material, where that material now exhibits an increase in magnitude of internal friction due to the presence of the added substance.

(9) As used herein, “friction modifier” means a substance added to a material in order to reduce the resistance that one surface or object encounters when moving over another.

(10) As used herein, “non-curing” means a sealant that does not need to be set up to reach optimum viscosity or modulus at a certain temperature, where set up includes, for example, hardening by means of a chemical reaction.

(11) As used herein, “sealing” means the application of a coating to a surface to make it substantially impervious to fluids (e.g., liquids and/or gases).

(12) As used herein, “thixotrope” means a substance, such as a fluid or gel, which has a viscosity that decreases when a stress is applied.

(13) As used herein, “viscoelastic” means a substance exhibiting both elastic and viscous behavior when deformed.

(14) As used herein, “liquid” means a substance that flows freely but is of constant volume.

(15) This invention as disclosed herein is based on a viscoelastic liquid, primarily silicone oil, including but not limited to, polydimethylsiloxane or chemically similar silicone lubricants, as would be apparent to the skilled artisan. Silicone polymers may be obtained in viscosities as low as 50 cSt to as high as 2,000,000 cSt. Although other oils may be used, silicone oils have a decided advantage. Silicone oils have extremely low volatility and high flash point. Silicone oils are chemically resistant and withstand temperatures from −50° F. to 500° F. Most silicone oils are considered food safe, are non-reactive and compatible with many different materials.

(16) The present invention as disclosed herein, may have a viscosity range of 20000 cSt to 500,000 cSt. The silicone oil may be fortified with builder(s) that help to form a barricade to reduce gas and/or liquid leakage to remarkably low atomic leak rates for which this invention is dedicated. Said builder(s) may also enhance the silicone oil's ability to hold against high pressure. As disclosed herein, the built silicone oil has exhibited an inverse relationship between applied pressure and sealing performance. That is, as the pressure in a system is raised, one would expect to observe the leak rate increase; however, inversely, it has been discovered that as the pressure is increased, the leak rate would drop. This is an unexpected result that occurs when all the builders are present at properly aligned ratios, in some, but not all of the trial formulations as disclosed herein. In embodiments, the silicone oil may be present in a range from about 50% to about 90% of the composition.

(17) One example of an optional building block would be a friction modifier. Addition of a friction modifier will aid in the ease of assembly and disassembly of the threaded parts. Silicone oil by itself has a low coefficient of friction and the addition of fine to ultra-fine PTFE powder or graphite or molybdenum disulfide may be useful but not vital to this disclosed composition. In embodiments, PTFE may be used as it is considered a food safe ingredient. The typical use level of PTFE may range from about 1% to about 50% by weight of the compound, including with a range of about 2% to about 20% by weight of the compound. PTFE may be Fine (F, i.e., particle sizes ranging from about 50 microns to about 250 microns) or Ultra-Fine (UF, i.e., particle sizes ranging from about 0.1 microns to about 50 microns).

(18) Another example of an optional building block may be a viscosity booster in the form of, for example, fumed silica or organoclays which are typically used to help increase the viscosity of oils. Such an optional viscosity booster may be considered useful to control the overall consistency of the finished product. In this invention, fumed silica may be the selected viscosity booster since it again is considered food safe. The fumed silica may be used at a level of about 0.5% to about 10% by weight of the compound, including with a range of about 1% to about 8% by weight of the compound.

(19) Another example of an optional building additive may be chosen from a long list of fillers and/or bulking agents. Typically, any fine to ultra-fine powder that is food safe, nonreactive to most liquids and gases, temperature tolerant and chemically stable may be used. Some inorganic examples used as fillers would include, but are not limited to, calcium carbonate, calcium sulfate and titanium dioxide or combinations thereof. Some organic examples of fillers would be fine to ultra-fine powdered plastics such as polyvinyl chloride (PVC), polyethylene or polypropylene or combinations thereof. These fillers may be present in concentrations of anywhere between about 1% to about 50% by weight of the compound, including with a range of about 10% to about 40% of the compound. However, care must be taken because adding too much filler will cause the viscoelastic effect to drop out and reduce the compound to a thixotrope or paste. To avoid this degradation, the percent of filler must be judicious. That is to say, the quantity of filler added should not exceed 30% to about 40% of total solids, inclusive of all other solid materials for the final formulation.

(20) The following examples are intended to illustrate but not limit the invention.

EXAMPLES

(21) Materials and Methods

(22) Fine (F) shall represent particles sizes ranging from 50 to 250 microns.

(23) Ultra-Fine (UF) shall represent particles sizes ranging from 0.1 to 50 microns.

(24) Helium Leak Detection Equipment and Method:

(25) A Leybold Helium Leak Detector model Phoenix L300i (Leybold USA, Inc., Glenwillow, OH) was calibrated to manufacturer's specifications. Testing was performed in a Bell Jar assembly. Thread sealant was applied in ample amounts onto the threads of ½ inch National Pipe Thread (NTP) galvanized pipe assembly. Fittings were torqued to about 70 in-lbs. With the fitting securely connected to the helium pressure line, the test sample was place inside the test chamber and evacuated. The test sample was pressurized to about 50 PSIG and the pressure increased by about 50 PSIG every 30 seconds for 15 minutes. Leak rates were observed and recorded.

(26) Results (see Table 1).

(27) TABLE-US-00001 TABLE 1 Time Pressure Example # 1 Example #2 Example #3 Example #4 (in (PSIG of Leak Rate Leak Rate Leak Rate Leak Rate minutes) He) (atm cc/sec) (atm cc/sec) (atm cc/sec) (atm cc/sec)  0:30   50 5.1 × 10.sup.−9 2.2 × 10.sup.−9 5.8 × 10.sup.−6 8.6 × 10.sup.−4  1:00  100 5.0 × 10.sup.−9 2.1 × 10.sup.−9 5.5 × 10.sup.−6 8.6 × 10.sup.−4  1:30  150 4.8 × 10.sup.−9 2.0 × 10.sup.−9 5.2 × 10.sup.−6 8.5 × 10.sup.−4  2:00  200 4.7 × 10.sup.−9 1.9 × 10.sup.−9 5.0 × 10.sup.−6 8.6 × 10.sup.−4  2:30  250 5.2 × 10.sup.−9 1.8 × 10.sup.−9 4.8 × 10.sup.−6 9.4 × 10.sup.−4  3:00  300 5.0 × 10.sup.−8 1.7 × 10.sup.−9 4.6 × 10.sup.−6 9.9 × 10.sup.−4  3:30  350 5.1 × 10.sup.−9 1.7 × 10.sup.−9 4.3 × 10.sup.−6 1.2 × 10.sup.−3  4:00  400 4.9 × 10.sup.−9 1.6 × 10.sup.−9 4.1 × 10.sup.−6 1.2 × 10.sup.−3  4:30  450 5.1 × 10.sup.−9 1.5 × 10.sup.−9 3.7 × 10.sup.−6 1.0 × 10.sup.−3  5:00  500 5.1 × 10.sup.−9 1.4 × 10.sup.−9 3.6 × 10.sup.−6 7.2 × 10.sup.−2  5:30  550 5.1 × 10.sup.−9 1.4 × 10.sup.−9 3.4 × 10.sup.−6 6.0 × 10.sup.−1  6:00  600 5.9 × 10.sup.−9 1.3 × 10.sup.−9 3.2 × 10.sup.−6 Failed  6:30  650 6.5 × 10.sup.−9 1.3 × 10.sup.−9 3.1 × 10.sup.−6  7:00  700 7.7 × 10.sup.−9 1.2 × 10.sup.−9 2.9 × 10.sup.−6  7:30  750 7.7 × 10.sup.−9 1.2 × 10.sup.−9 2.7 × 10.sup.−6  8:00  800 9.0 × 10.sup.−9 1.1 × 10.sup.−9 2.6 × 10.sup.−6  8:30  850 Failed 1.1 × 10.sup.−9 2.5 × 10.sup.−6  9:00  900 1.1 × 10.sup.−9 2.4 × 10.sup.−6  9:30  950 1.0 × 10.sup.−9 2.3 × 10.sup.−6 10:00 1000 1.0 × 10.sup.−9 2.2 × 10.sup.−6 10:30 1050  9.6 × 10.sup.−10 2.1 × 10.sup.−6 11:00 1100  9.5 × 10.sup.−10 2.0 × 10.sup.−6 11:30 1150  9.2 × 10.sup.−10 2.0 × 10.sup.−6 12:00 1200  8.6 × 10.sup.−10 1.8 × 10.sup.−6 12:30 1250  8.4 × 10.sup.−10 1.8 × 10.sup.−6 13:00 1300  8.2 × 10.sup.−10 1.7 × 10.sup.−6 13:30 1350  8.0 × 10.sup.−10 1.6 × 10.sup.−6 14:00 1400  7.5 × 10.sup.−10 1.5 × 10.sup.−6 14:30 1450  7.5 × 10.sup.−10 1.5 × 10.sup.−6 15:00 1500  7.0 × 10.sup.−10 1.5 × 10.sup.−6

(28) Example #1. Viscoelastic liquid (see Table 2)

(29) TABLE-US-00002 TABLE 2 Silicone Oil 85% PTFE (UF) 10% Fumed Silica  5%

(30) Viscosity of Example #1 is about 80000 cSt. Percentages are wt/wt.

(31) At first glance, failure of the sealant is seen @ 850 PSIG. However, this is actually a better pressure holding capacity than most commercially available thread sealants (see Example #4). In fact, most of the non-curing thread sealants observed fail at about 350 PSIG with helium. Commercially available thread sealants that hard set or cure usually fail to reach 700 PSIG with some failing as low as 200 PSIG. For comparison commercial thread sealants have leak rates in the range of 10.sup.−3 to 10.sup.−4 before failing.

(32) Example #2 Viscoelastic liquid (see Table 3).

(33) TABLE-US-00003 TABLE 3 Silicone Oil 79% PTFE (UF)  8% Fumed Silica  3% CaCO.sub.3 10%

(34) Viscosity of Example #2 is about 90000 cSt. Percentages are wt/wt.

(35) With the addition of CaCO.sub.3 and reduction of PTFE and Fumed Silica, Example #2 reaches the pressure test limit of 1500 PSIG. The phenomena of inverse pressure to leak rate was observed in Example #2. As may be seen, the leak rate starts out in the 10.sup.−9 range then as the pressure increases, the leak rate slows another order of magnitude to the 10.sup.−10 .

(36) Example #3 Viscoelastic Liquid (see Table 4)

(37) TABLE-US-00004 TABLE 4 Silicone Oil 84% PTFE (UF)  5% Fumed Silica  3% CaCO.sub.3  8%

(38) Viscosity of Example #3 is about 65000 cSt. Percentages are wt/wt.

(39) Reducing the total solids to just 16% results in higher measured leak rates. The inverse pressure to leak rate is still observed.

(40) Example #4 Paste

(41) Is formulated following Example #2 from U.S. Pat. No. 4,548,960 (see Table 5).

(42) TABLE-US-00005 TABLE 5 Talc 45 TiO.sub.2  3 Castor Oil 40 Teflon Fibers 12

(43) Viscosity of Example #4 is about 95000 cSt. Higher initial leak rates with this product versus the present compositions were observed. The leak rate is linear with leakage increasing as more pressure is applied before finally failing.

(44) Although the invention has been described with reference to the above examples, it will be understood that modifications and variations are encompassed within the spirit and scope of the invention. Accordingly, the invention is limited only by the following claims.