Gland Packing Research Articles

Sealing characteristics of gland packing (2nd report, Analysis of the distribution of the contact pressure and the frictional force in tightened packing.

This paper presents a method to calculate the distribution of the contact pressure between some packings and the stem, the change in the height of the piled-up packings and the axial-frictional force, at a given gland pressure for various combinations of asbestoid and graphitic packings. The analytical contact pressure between the graphitic packings and the stem is greater than that compared to using of asbestoid packings, because the value of the normal-to-axial pressure ratio of the graphitic packing is larger than that of the asbestoid one. The contact pressure on the packings tightened initially under the free-stem condition, and at the pushing and pulling of the stem, is larger than that tightened under a fixed-stem condition. The reaction pressure at the oposite side of the gland, the displacement of the packings and the axial-frictional force, under pulling and pushing of the stem, were experimentally obtained. These experimental observations agree fairly well with the analytical results.

Theoretical determination of the characteristics of pliant and loose gland packings

This paper cites the results of the investigation into the distribution of axial and lateral pressures along the height of the packing, making it possible to determine the coefficient of lateral pressure and the coefficient of static friction for 2 packing materials: 1) for a pliant packing consisting of 30% of asbestos, 35.5% of cylinder oil, 7.0% of paraffin, 15% of graphite, and 12.5% of ground talc; 2) for a friable material used for making rings of the seal AG-50 and containing 42.5% of asbestos, 46.8% of graphite, 2.5% of aluminum powder, and 8.2% of industrial water.

Certification corner

This portion of “Certification Corner” requires definitions of suction lift, head, capacity, centrifugal pumps, pump efficiency, shafts, impellers, static suction head, squirrel cages, friction loss, wear rings, cases, brake horsepower, packing glands, and prime movers.

Calculation of hermeticity of packing glands with dry unimpregnated packing

Calculation of hermeticity of packing glands with dry unimpregnated packing

Automatic proportioning of the liquid components in the synthesis of copolymers of acrylonitrile

3. The glands, rams, and valves of the hydraulic cylinders fail prematurely, the reason being that the design of the proportioner unit incorporates a water circuit for washing-out, forming the hydraulic seal, and cooling at a flow rate of 5-10 liter/h. The water enters the systemtogether with the proportioned components so that the reaction is attenuated. The gland packings do not prevent leakage of toxic components llke nitrile of acrylic acid (NAA) and methyl ether of acrylic acid (MA) into °the workroom so thatthe concentration of NAA and MAvapors in the atmosphere of the room is sometimes 10-15 times higher than the maximum permitted concentration (MPC).

Machine for manufacturing gland packing for gate valves with Dn=50 mm

Machine for manufacturing gland packing for gate valves with Dn=50 mm

Locating and Sizing Air‐Release Valves

Air can enter a pipeline in any number of insidious ways: through packing glands, leaky joints, and even from the water itself. Unless passage is fast enough to purge any buildup of air at high points along the pipe line, large air pockets can form that will impede the flow of water. Properly located air‐release valves can minimize the problem.

Wear of frictional surfaces in a gland seal with a soft packing

In rota t ion of a shaft having a gland seal with a soft packing, the f i r s t two packing r ings which a re under the gland at the s t a r t of the stuffing box (Fig. la) have the m a x i m u m wear , amounting to 70% of the wear in the whole gland packing. At the s ame t ime, the l as t packing r ings a re hard ly worn at all, and, according to [1] prove to be superf luous . This conclusion is based on the equation which desc r ibes the law of dis tr ibut ion of radia l p r e s s u r e in packing along the seal height under stat ic conditions, in the absence of p r e s s u r e f rom the medium being sealed under the gland (Fig. lb) :

New standardized high-pressure packing glands with Teflon rings

New standardized high-pressure packing glands with Teflon rings

How to determine the lateral pressure and shrinkage coefficients of soft gland packings

How to determine the lateral pressure and shrinkage coefficients of soft gland packings

Investigation of the operation of Teflon gland packings in high pressure compressors

Investigation of the operation of Teflon gland packings in high pressure compressors

Rubber wear during friction against a metallic surface (with reference to packing glands for high-speed machine elements)

The wear of rubber in sliding against a metallic surface at high sliding velocities, which causes temperatures at the point of contact of the order of 100–250°C, has been studied. The theoretical equation obtained relates the wear of rubber during sliding against a metallic surface to its elastic-strength and friction properties and to the geometrical characteristics of the metal surface. Satisfactory agreement between theory and experiment is found.

Basing the packing gland of a high pressure pump

Basing the packing gland of a high pressure pump

Investigation of stress relief in a compressor packing gland

Investigation of stress relief in a compressor packing gland

Lengthening service life of gland packing in preliminary compressors

Lengthening service life of gland packing in preliminary compressors

Effect of Coulomb Friction on the Vibrations of a System with Elastically Supported Viscous Damper : 1st Report, Free and Transient Vibrations

In this report, the effect of Coulomb friction brought about from the packing gland of the damper on the free and transient vibrations of the above system is considered with respect to some numerical examples. The result shows (1) that a cycle of free vibration consits of two motions, one the motion when the friction is infinite and the other the motion with combined Coulomb friction and viscous damping, and (2) that the transient state while the system runs over a bump (shaped like a portion of sinusoidal curve) is regarded as a chain of fragmentary pieces of the two kinds of motion stated above. The existence of the motion when the damper is momentarily stuck-up gives a negative effect on the diminishing of the amplitude of the free-vibration of the system, but comparing the transient states with those of the system with no friction, a larger decrement of the amplitude of the initial response may occur in some cases according to the combination of the magnitude of friction, height of projection and the passing speed over it.

Thyratron-Controlled Stirrer or Pump for Pressurized Systems

An apparatus is described which provides a simple means of obtaining stirring or pumping action in a pressurized system. Since no packing glands are employed, the device is leak-proof. The required mechanical action is provided by reciprocating motion of a soft-iron armature enclosed in the system and driven by a pair of electromagnetic coils. Input to the coils is provided by a thyratron-controlled circuit. The circuit and constructional details are given.

A Review and Analysis of Equipment for Running Electrical Cables Under Pressure

Abstract Developments in permanent-type well completion techniques have accentuated the need for improved equipment to handle cables under pressure. Existing conventional packoff devices were tested and their dynamic performance established at 200 to 600 psi with electrical conductor cables. A new packoff technique is reported that permits operating stranded cables at moderate running speeds up to pressure as high as 3,000 psi. In the higher pressure ranges a new commercial device is reported for running cables against well pressure as high as 6,000 psi. These new developments open wide the doors to improved well completion practices, resulting in improved well productivity and more precise well control. Introduction Field experience with some phases of permanent-type well completions uncover a need for more adequate and simplified means of running conductor cables into wells under pressure. This paper concerns armored electrical cables usually used in service company work, although the findings are equally applicable to other stranded cables. The construction of a reverse armor electric conductor cable is such that 20 per cent of the cross section area is pore space. The difficulty in sealing this amount of space has dictated, in the past, the use of small diameter cables for even medium pressure work. Early experiments with packing glands used with conductor cables revealed that a complete high-pressure shutoff could only be obtained by filling the pore space within the cable with heavy grease or packing gland pressures, which prohibited or retarded cable movement. Recently a new concept has developed of handling cables under pressure. Tests have shown that with a stranded cable located in a closely fitting metal sleeve, the flow through and around the cable is not great and can be controlled. This is known as the controlled blow-by principle and its use has opened up a new approach to the stuffing box problem.

LONGITUDINAL VIBRATION OF MARINE PROPELLER SHAFTING

Synopsis.Longitudinal vibration of the propeller shafting has been the cause of seizure, serious scoring and excessive wear in the flexible couplings of Naval vessels and has in some cases given rise to unacceptable vibration of the bridge structure. Other defects such as difficulty in retaining stern gland packing, wear and loosening of stern tube bushes and loosening of rivets in thrust block seats have been attributed to the same cause. In three‐ and four‐shafted ships the vibration is aggravated when turning because the blades of the inner propeller on the outside of the turn cut into the slip stream of the outermost wing propeller. It has been necessary on this account, in the majority of big ships, to reduce the power on the outermost wing shaft when turning at high speed, a procedure which introduces difficulties in control and reduces manoeuvrability.The present paper describes how theory suggested that the vibration was magnified by resonance between the natural frequency of the system and the impulses arising from the number of blades on the propeller, and predicted that the amplitude would be reduced to an acceptable figure by changing the number of blades. Details are given of the vibration trials carried out to confirm the theory, and it is seen that the predicted improvement is, in fact, achieved. The trial results are worked up to give fundamental data as to thrust block flexibility, entrained water, thrust variation, damping factor, and the effect of turning. Using this information complete calculations are set out for a particular line of shafting, showing the effect of two possible thrust block positions and of using three‐ or five‐bladed propellers. A second example treats the case of a very long shaft and shows that there is a need for further data. Using the worked examples as a basis for discussion, general principles are suggested by the application of which trouble may be cured in existing ships and avoided in new construction.

An Infra-Red Spectrophotometer for Industrial Research

An infra-red spectrophotometer has been designed for the wide variety of problems which arise in an industrial research laboratory. The source of radiation is a Nernst glower, the dispersing unit a 10 × 15 cm sodium chloride prism, and the detector is a compensated thermopile. The output of the thermopile is amplified with a contact modulated amplifier. The installation is comparatively insensitive to mechanical vibration and fast temperature changes. The instrument is enclosed in a vacuum tank to prevent interference from absorption by extraneous gases. Driving motors for prism rotation and slit adjustments are outside the vacuum. Rotary motion is transmitted through the walls of the vacuum tank by means of magnetic drives; this avoids the use of any form of packing gland. Ink-line records of the spectral range from 3 to 15μ can be made automatically in 30 minutes. The instrument is operated semiautomatically for “spot work” in making quantitative analyses after spectral positions and proper calibrations have been made.