GB2148339A - Packing material - Google Patents
Packing material Download PDFInfo
- Publication number
- GB2148339A GB2148339A GB08327669A GB8327669A GB2148339A GB 2148339 A GB2148339 A GB 2148339A GB 08327669 A GB08327669 A GB 08327669A GB 8327669 A GB8327669 A GB 8327669A GB 2148339 A GB2148339 A GB 2148339A
- Authority
- GB
- United Kingdom
- Prior art keywords
- packing material
- material according
- lubricant
- zro2
- weight
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000012856 packing Methods 0.000 title claims abstract description 39
- 239000000463 material Substances 0.000 title claims abstract description 20
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims abstract description 22
- 239000000314 lubricant Substances 0.000 claims abstract description 21
- 239000007787 solid Substances 0.000 claims abstract description 15
- 239000011521 glass Substances 0.000 claims abstract description 14
- 239000000203 mixture Substances 0.000 claims abstract description 6
- -1 polytetrafluoroethylene Polymers 0.000 claims abstract description 6
- 230000008018 melting Effects 0.000 claims abstract description 5
- 238000002844 melting Methods 0.000 claims abstract description 5
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims abstract description 4
- 239000004810 polytetrafluoroethylene Substances 0.000 claims abstract description 4
- 239000003513 alkali Substances 0.000 claims abstract description 3
- 239000004615 ingredient Substances 0.000 claims abstract description 3
- NBVXSUQYWXRMNV-UHFFFAOYSA-N fluoromethane Chemical group FC NBVXSUQYWXRMNV-UHFFFAOYSA-N 0.000 claims description 5
- 229920005989 resin Polymers 0.000 claims description 5
- 239000011347 resin Substances 0.000 claims description 5
- 235000019271 petrolatum Nutrition 0.000 claims description 4
- 239000000835 fiber Substances 0.000 claims description 2
- 229910044991 metal oxide Inorganic materials 0.000 claims 1
- 150000004706 metal oxides Chemical class 0.000 claims 1
- 239000002253 acid Substances 0.000 abstract description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 abstract description 6
- 150000007513 acids Chemical class 0.000 abstract description 3
- 229910052681 coesite Inorganic materials 0.000 abstract description 3
- 229910052906 cristobalite Inorganic materials 0.000 abstract description 3
- 239000000377 silicon dioxide Substances 0.000 abstract description 3
- 235000012239 silicon dioxide Nutrition 0.000 abstract description 3
- 229910052682 stishovite Inorganic materials 0.000 abstract description 3
- 229910052905 tridymite Inorganic materials 0.000 abstract description 3
- 229910000287 alkaline earth metal oxide Inorganic materials 0.000 abstract description 2
- 239000010425 asbestos Substances 0.000 description 3
- 229910052895 riebeckite Inorganic materials 0.000 description 3
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000009954 braiding Methods 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 229910052620 chrysotile Inorganic materials 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 239000003365 glass fiber Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 1
- 239000011398 Portland cement Substances 0.000 description 1
- 239000006087 Silane Coupling Agent Substances 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000002612 dispersion medium Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 229940097789 heavy mineral oil Drugs 0.000 description 1
- XWHPIFXRKKHEKR-UHFFFAOYSA-N iron silicon Chemical compound [Si].[Fe] XWHPIFXRKKHEKR-UHFFFAOYSA-N 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000010445 mica Substances 0.000 description 1
- 229910052618 mica group Inorganic materials 0.000 description 1
- 239000006060 molten glass Substances 0.000 description 1
- CWQXQMHSOZUFJS-UHFFFAOYSA-N molybdenum disulfide Chemical compound S=[Mo]=S CWQXQMHSOZUFJS-UHFFFAOYSA-N 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- PXXKQOPKNFECSZ-UHFFFAOYSA-N platinum rhodium Chemical compound [Rh].[Pt] PXXKQOPKNFECSZ-UHFFFAOYSA-N 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 229920002050 silicone resin Polymers 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000001117 sulphuric acid Substances 0.000 description 1
- 235000011149 sulphuric acid Nutrition 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 239000000080 wetting agent Substances 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J15/00—Sealings
- F16J15/16—Sealings between relatively-moving surfaces
- F16J15/18—Sealings between relatively-moving surfaces with stuffing-boxes for elastic or plastic packings
- F16J15/20—Packing materials therefor
- F16J15/22—Packing materials therefor shaped as strands, ropes, threads, ribbons, or the like
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Gasket Seals (AREA)
- Sealing Devices (AREA)
- Sealing Material Composition (AREA)
Abstract
Packing material suitable for use in pumps and the like which are required to withstand strong acids comprises braided glass yarn impregnated with solid lubricant of melting point above 200 DEG C, such as polytetrafluoroethylene, the fibres of the yarn having a content of combined zirconia (ZrO2). Such fibres can be made from a composition whose predominant ingredients by weight are SiO2, 55-75%; alkali plus alkaline earth metal oxide, 10-25%; and ZrO2, 5-25%.
Description
SPECIFICATION
Packing material
This invention relates to packing material suitable for use in pumps and the like which are required to withstand strong acids.
One known form of acid-resistant packing for pumps takes the form of braided asbestos yarn impregnated with a solid lubricant, such as fluorocarbon resin, eg polytetrafluoroethylene or polymonochlorofluoroethylene.
The present invention provides a non-asbestos alternative to such acid-resistant packing, and depends on our discovery that glass fibres of the kind sold for use in cement reinforcement, which are made with a content of combined zirconia (ZrO2) to give them improved resistance to the strongly aikaline conditions (pH about 12) prevailing in a matrix of set Portland cement, also have very good resistance to acids; and that such glass gibres are resilient enough to be formed into packing, and sufficiently non-abrasive to enable use as packing without unduly scoring the rotor shaft of a pump or the like which they contact when the packing is put to use.
In general, such fibres are made from a composition whose predominant ingredients are SiO2, 55-75%, alkali plus alkaline earth metal oxide, 10-25%; and ZrO2,5-25% by weight.
One particularly suitable form of fibre is that commercially available under the registered trade mark
Cem-FIL, whose composition in weight % is:
SiO2 62
Na2O 14.8
CaO 5.6
ZrO2 16.7 At203 0.8
TiO2 0.1
Fibres of this kind are described in British Patent specification 1 290 528 (in which % compositions are given in molecular weight percentages, not as here in ordinary weight percentages); and the fibres described in that specification can in general be used in the method of the present invention. So also can those described in British Patent specifications 2 071 081 and 1 459 385.
According to the invention, therefore, packing material comprises braided glass yarn impregnated with fluorocarbon resin or other solid lubricant of melting point above 200"C, the fibres of said glass yarn having a content of combined ZrO2.
Preferably, the weight proportion glass: solid lubricant is in the range 1:2-4:1, particularly 1:2-2:1. The solid lubricant is, as already indicated, a fluorocarbon resin, but may alternatively be a silicone resin, graphite, mica or molybdenum disulphide.
The packing material preferably also includes a secondary lubricant, that is to say one which has a melting point below 200"C. The secondary lubricant, which may form up to about 20% by weight of the packing material, fills the interstices between the glass yarn and the particles of solid primary lubricant and facilitates the formation of a liquid-impervious structure when the packing material is compressed by tightening the flange bolts of the stuffing box of a pump or the like. Petroleum jelly is a very suitable secondary lubricant.
To make the packing material of the invention, yarn made from zirconia-containing glass fibre in an entirely conventional way is impregnated with solid lubricant, and several of the impregnated yarns (at least four) are then formed into a braided structure, again by entirely conventional means. The solid lubricant can be introduced into the yarn (and, of course, the yarn surface is then simultaneously coated with solid lubricant) by treating the yarn with a suspension of the solid lubricant in a liquid, eg water, which is easily removable by evaporation, and then evaporating the dispersion medium. The secondary lubricant can be introduced into the impregnated braided structure by immersing the latter in that lubricant in the liquefied state, draining off excess liquid, and allowing the material taken up to re-set to the solid state.
The invention is further illustrated by the following example:
Example
A 1200 tex roving of 12 m-diameter glass filaments was made from a ZrO2-containing glass of composition according to Example 2 in British Patent Specification 1 459 385 by assembly winding 8 x 150 tex strands, each strand being conventionally formed by melt-drawing 200 filaments from a 200-hole platinum-rhodium bushing which was directly electrically heated and supplied with molten glass from a gas-fired furnace. Each strand on formation was passed over a liquid-applicator roller to apply about 1/2-1 % dry weight of a conventional protective lubricant dressing, being an aqueous emulsion of polyester, silane coupling agent and wetting agent.
The 1200 tex roving so formed was then passed through a bath of aqueous dispersion (50% solids content) of polyetrafluoroethylene (PTFE), then through a drying tower at about 120"C to remove residual water, and re-wound into small parallel build packages suitable for use on a maypole braiding machine. The dried
PTFE-coated roving contained about 55% by weight ZrO2-containing glass and about 45% of weight PFTE.
The wound packages of PTFE-impregnated roving were placed upon the carriages of an 8-spindle maypole braiding machine, and square packings were made as follows:
6.5 mm square packing 9.5 mm square packing
Spindle Yarns 2 ends of roving 3 ends of roving
Core Yarn 8 ends of roving 5 ends of roving
Corner Yarns 2 ends of roving 3 ends of roving
Boss size 6.5 mm square 9.6 mm square Plaitsfdm 22 18
Coils of braided packing were then steeped for 20 minutes in liquefied refined petroleum jelly at 80"C, allowed to drain and cool, and finished by passing through a 4-roller squaring maching to finally define the size and compact the yarn assembly.
The finished packing comprised:
47% by weight ZrO2-coating glass filaments
38% by weight polytetrafluoroethylene
15% by weight refined petroleum jelly
The 6.5 mm square packing is illustrated in the accompanying drawing. In the drawing, 1 represents impregnated core yarns, 2 represents corner yarns and 3 represents the outer cover (spindle yarns).
The acid-resistant properties of packing prepared as described in the Example were compared with those of greased and graphited white asbestos packings by using the packings in a stuffing box (internal diameter, 53/8") in which a vertical stirrer shaft of 14% silicon iron (diameter 4.5") was running at 24 rpm. The packing of the inner side of the stuffing box was in continuous contact with sulphuric acid fumes (95% concentration; temperature up to 320 C).
The asbestos packings lasted less than five weeks under these conditions before leaking uncontrollably, whereas packings according to the invention were removed from the stuffing box eight weeks with no signs of degradation.
In a further test, a horizontal 1" diameter stainless steel shaft carrying an impeller was run at speeds up to 3,000 rpm in the stuffing box (internal diameter 1.5") of a pump, while acid (sulphuric or nitric) at various concentrations and temperatures was in contact with the packing on the inside face of the stuffing box.
Packings according to the invention showed no degradation after several weeks, whereas white asbestos packings impegnated with PTFE dispersion and heavy mineral oil were severely degraded.
Claims (9)
1. Packing material comprising braided glass yarn impregnated with solid lubrucant of melting point above 200 C, the fibres of said glass yarn having a content of combined ZrO2.
2. Packing material according to Claim 1, in which the weight proportion glass: solid lubricant is in the range 1:2-4:1.
3. Packing material according to Claim 1 or 2, in which the solid lubricant is a fluorocarbon resin.
4. Packing material according to Claim 3, in which the fluorocarbon resin in polytetrafluoroethylene.
5. Packing material according to any of Claims 1-4, which also includes a lubricant of melting or softening point below 200 C.
6. Packing material according to Claim 5, in which said lubricant is a petroleum jelly.
7. Packing material according to Claim 5 or 6, in which said lubricant forms up to 20% by weight of the packing material.
8. Packing material according to any one of Claims 1-7, in which the fibre of said glass yarn is made from a composition whose predominant ingredients are SiO2,55-75%; alkali plus alkaiine earth metal oxide, 10-25%; and ZrO2,5-25% by weight.
9. Packing material substantially as described herein with reference to the Example.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08327669A GB2148339B (en) | 1983-10-15 | 1983-10-15 | Packing material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08327669A GB2148339B (en) | 1983-10-15 | 1983-10-15 | Packing material |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8327669D0 GB8327669D0 (en) | 1983-11-16 |
| GB2148339A true GB2148339A (en) | 1985-05-30 |
| GB2148339B GB2148339B (en) | 1986-09-24 |
Family
ID=10550278
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08327669A Expired GB2148339B (en) | 1983-10-15 | 1983-10-15 | Packing material |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2148339B (en) |
-
1983
- 1983-10-15 GB GB08327669A patent/GB2148339B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2148339B (en) | 1986-09-24 |
| GB8327669D0 (en) | 1983-11-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |