Sealant material

Abstract

A sealant material for sealing threaded pipe joints that is a multifilament or spun polyphenylene sulfide yarn and a joint sealing composition comprising a silicone oil or a natural oil with a smoke point of about 230 C. or higher. The polyphenylene sulfide yarn is coated with the joint sealant composition. The material forms an effective seal and is resistant even when used in systems in which it is exposed to temperatures in excess of 280 C. The material may be provided in a dispenser.

Claims

1. A sealant material for sealing joints consisting of: (a) a multifilament or spun yarn constructed from polyphenylene sulfide; and (b) a joint sealing composition comprising at least one of a silicone oil or a natural oil with a smoke point of about 230 C. or higher, wherein the polyphenylene sulfide yarn is coated with the joint sealant composition in an amount from about 20 to about 40%, w/w on from about 60 to about 80% w/w yarn.

2. A sealant material according to claim 1 wherein the silicone oil is selected from polydimethylsiloxane terminated with methyl or substituted with phenyl groups.

3. A sealant material according to claim 1 wherein the natural oil is selected from at least one of avocado oil, safflower oil, rice bran oil, soya bean oil and sesame oil.

4. A sealant material according to claim 1 wherein the yarn is a polyphenylene sulfide spun yarn and the joint sealing composition comprises a silicone oil.

5. An article of manufacture comprising a sealant material according to claim 1 packaged in a dispenser from which the sealant material can be supplied for direct application to a joint to be sealed.

6. A sealant material for sealing joints consisting of: (a) a multifilament or spun yarn; and (b) a joint sealing composition comprising a natural oil, wherein the natural oil is selected from at least one of avocado oil, safflower oil, rice bran oil, soya bean oil and sesame oil.

7. A sealant material for sealing joints consisting of: (a) a polyphenylene sulfide spun yarn; and (b) a joint sealing composition comprising methyl terminated polydimethylsiloxane.

8. A sealant material according to claim 7 wherein the joint sealing composition comprises by weight about 50 to 80% inert filler.

9. A sealant material according to claim 7 wherein the joint sealing composition comprises a combination of talcum, calcium carbonate, and poly (methyl methacrylate) microbeads.

10. A sealant material according to claim 7 wherein the joint sealing composition comprises by weight about 20 to 40% methyl terminated polydimethylsiloxane.

11. A sealant material for sealing joints consisting of: (a) a multifilament or spun yarn constructed from polyphenylene sulfide; and (b) a joint sealing composition comprising at least one of a silicone oil or a natural oil with a smoke point of about 2300 C or higher, wherein the polyphenylene sulfide yarn is coated with the joint sealant composition, wherein the silicone oil is methyl terminated polydimethylsiloxane and the natural oil is selected from at least one of avocado oil, safflower oil, rice bran oil, soya bean oil and sesame oil.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a drawing of a test assembly used in the Experimental section below; and

(2) FIG. 2 is a drawing of a threaded pipe joint with the sealant material applied thereto as described in the Experimental section below.

DETAILED DESCRIPTION

(3) Sealant materials according to the present invention were prepared as set out in the following Experimental section.

(4) Experimental

(5) The materials used were as follows:

(6) TABLE-US-00001 Name Material/Composition Yarn 1 polyphenylene sulfide multifilament yarn Yarn 2 polyphenylene sulfide spun yarn Coating a1 28% Methyl terminated PDMS 5% talcum 64% Calcium Carbonate (inorganic filler) 3% PMMA microbeads (polymeric filler for reworkability and sealing) Coating b1 24% avocado oil 68% Calcium Carbonate (inorganic filler) 5% talcum 3% PMMA microbeads (polymeric filler for reworkability and sealing) Coating a2 28% Methyl terminated PDMS 5% talcum 64% Calcium Carbonate (inorganic filler) 1.5% PMMA microbeads (polymeric filler for reworkability and sealing) 1.5% PTFE (polymeric filler) Coating b2 24% avocado oil 68% Calcium Carbonate (inorganic filler) 5% talcum 1.5% PMMA microbeads (polymeric filler for reworkability and sealing) 1.5% PTFE (polymeric filler)

(7) Two yarns of type Yarn 1 were combined together by placing them side-by-side and drawing them through a batch of paste. (The paste was used to hold them together as they were not twisted or spliced together in anyway.) Two yarns of type Yarn 2 were also combined together in the same way by placing them side-by-side and drawing them through a batch of paste.

(8) The paste used in each instance is identified as a1, a2, b1 or b2 in the table above and the components of each paste are listed in that table also. The Yarns are also identified in the table above.

(9) The emerging wet yarn was wound off onto rolls until a weight of approx 0.5-0.8 g/m of yarn was achieved.

(10) Testing was performed on assemblies made using new (unused) pipes and fittings cut according to EN 10242 having no visible defects. Recommended test parts are ISO 7-1 quality (and parts of this quality were used). The test assembly 1 used is shown in FIG. 1 below and consists of a pressure connection 4, a 1.5-0.5 (3.8-1.3 cm) reducer, and an equal barrel nipple 3, a 1.5 (3.8 cm) socket and a 1.5 (3.8 cm) stopper. Sockets employed generally have parallel threads and tapered stoppers.

(11) The male threads 7 were roughened using a metal saw. The male and female threads 7 were cleaned using a steel brush. The product was applied to the male threads 7 of the test joints 9,10,12. One thread 11 was left in a visible position to allow assembly into the sockets. Five winds of the product were applied to the next thread and wound back over five threads, then wound forward to the start, and back again, applying in a criss-cross fashion as shown in FIG. 2 below. The thread was cut off and the trailing end of the product tucked into the nipple or stopper so that it is not hanging loose.

(12) The test pieces were assembled as shown in FIG. 1 using a torque wrench to apply an input torque of 150 Nm. Excess product was removed using a steel brush. The samples were allowed to cool to room temperature before testing. (Heat may be produced due to friction.)

(13) The parts and in particular the joints were then tested according to Standard EN751-2 Screening Test as follows.

(14) An appropriate connector was attached to the open end of the test assembly and connected to an air pressure source.

(15) The test assembly was pressurised to 7.53 bar (0.75 MPa0.3 MPa) with air or nitrogen.

(16) The assembly was immersed in a water bath (room temperature) and inspected for leakage. Leakage is determined by the appearance of bubbles during the immersion period, ignoring those noted during the first 15 seconds of immersion.

(17) Joints 9 and 10 (see FIG. 1) were turned back by 45 and the assembly was again immersed and tested again as described above.

(18) Environmental Resistance Tests

(19) Once tested as above for instant seal, test assembles were filled with water, stoppered (at the pressure connector joint) and stored at quoted temperatures and corresponding pressures for 1 week. The stopper is then removed, test pieces were emptied, and joints were tested again as above.

(20) TABLE-US-00002 Resistance Resistance Resistance to Steam to Steam to Steam Rework- at 200 deg at 250 deg at 280 deg ability C., C., C., as defined pressure pressure pressure Instant by of 17 bar of 40 bar of 65 bar Yarn Coating Seal EN 752-1 (1.7 MPa) (4.0 MPa) (6.5 MPa) 1 (a1) 1 (a2) 1 (b1) 1 (b2) 2 (a1) 2 (a2) 2 (b1) 2 (b2)

(21) The main difference between coating a1 and b1 respectively and a2 and b2 respectively is that avocado oil was used instead of PDMS.

(22) For comparison, the below table shows results based on using the same formulations except for using polyamide yarns with the above coatings:

(23) TABLE-US-00003 Resistance Resistance Instant to Steam at to Steam at Yarn Coating Seal 250 deg C. 280 deg C. PA 4,6 (b2) X X PA 6,6 (a2) X X PA 6,6 (b2) X X Loctite 55 X X

(24) PA 4,6=polyamide 4,6; PA 6,6=polyamide 6,6. LOCTITE 55 is a pipe sealant material; it is a coated nylon thread sealant product 4 where the coating is a paste made from hydroxy terminated polydimethylsiloxane with inert fillers including calcium carbonate, talc, and polytetrafluoroethylene. Based on the comparative results in the table above it is expected that using PA 4,6 and PA 6,6 with compositions a1 and b1 would also fail as seals formed using the a2 and b2 compositions were found to perform better than those formed using the a1 and b1 compositions respectively.

(25) It is clear from the foregoing experimental work that the sealant materials of the present invention clearly provide advantages compared to other compositions and have been carefully formulated for optimum properties.

(26) The words comprises/comprising and the words having/including when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

(27) It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.