定价： 156元 / 折扣价： 133 元 加购物车

定价： 156元 / 折扣价： 133 元 加购物车

定价： 156元 / 折扣价： 133 元 加购物车

定价： 156元 / 折扣价： 133 元 加购物车

定价： 156元 / 折扣价： 133 元 加购物车

定价： 156元 / 折扣价： 133 元 加购物车

定价： 156元 / 折扣价： 133 元 加购物车

定价： 0元 / 折扣价： 0 元 加购物车

定价： 156元 / 折扣价： 133 元

5.1 Cast iron Yankee dryers can be up to 6.7 m [22 ft] in diameter, 7.3 m [24 ft] long, and weigh 91 000 Kg [100 tons], or more (refer to Fig. 1). Vessel thickness measurements are available from the paper/tissue machine operator. Cast iron is a brittle metal and has no specific yield point. Yankee dryers must maintain specific dimensional tolerances. When a pressurized Yankee or steam heated paper dryer (SHPD) remains stationary, it fills with condensate at a rapid rate. In an hour, a steam pressurized Yankee or SHPD can fill half way with condensate, doubling the weight on the frame, and the floor. Some Yankee owners have corporate requirements that a cast iron Yankee dryer remain stationary for 1/2 h, then rotation is required. Permission is required, if the Yankee is to remain stationary for more time. This issue should be discussed with the responsible person prior to the examination.FIG. 1 Yankee Dryer Drum5.2 Yankee dryers operate under a heated hood. The hood is in close proximity to the Yankee shell and allows only inches of clearance for the top half of the vessel.5.3 Cast iron steam heated paper machine dryers are 2 m [6 ft] in diameter, or more, and may be 9 m [30 ft] long.5.4 Grey cast iron experiences a continuing reduction in elastic modulus as it is stressed to increasing higher levels. It is prudent not to stress grey cast iron material beyond its operating stress level.5.5 Flaws to be found are the same as those in any cast and machined product. Attempts have been made to characterize strength properties of cast irons in compact tension tests. In a TAPPI sponsored laboratory study, two out of three cast iron compact tension specimens experienced unplanned failures. From that experience it was cautioned that cracks initiated and grew faster than expected resulting in brittle fracture before the process could be halted. The failure of these two coupons demonstrated the rate in which cracks can grow in these materials and the material’s inability to stop a crack once it begins to grow. In each case, crack advance was extremely rapid and without warning. (See Note 1.)NOTE 1: Alleveto, C., and Williams D., Acoustic Emission Evaluation of Yankee Dryer Shell Material, 1991 TAPPI Engineering Conference Proceedings, pages 475-480.5.6 Maximum Examination Pressure—Maximum Allowable Working Pressure for cast iron vessels is set based on ASME (Section VIII) pressure calculations based on thickness, radius, and material strength values, and will not exceed 10 bar [160 psi] and 230 °C [450 °F] (Specification A278/A278M). When vessels are pressurized, anomalies produce emission at pressures less than normal fill pressure. Historically, if there is damage in a cast iron pressure boundary, AE activity will begin at load/stress levels less than 50 % of operating. Defects as small as 3 mm [1/8 in.] have been found using AE, during steam pressurization to operating pressure.5.7 Pressure increments should not exceed 0.35 bar [5 psi] per minute. If pressurization medium is to be steam, the Yankee should have been through the warm-up process.5.8 Yankee dryers may receive a subsequent examination, if necessary, after the Yankee is rotated to remove any condensate present.5.9 Pressurization Schedule—Pressurization should proceed at rates that allow achieving maximum examination pressure within a 30 minute period. During pressurization, pressure holds are not necessary; however, they may be useful for reasons other than measurement of AE. Pressure hold upon achieving maximum examination pressure may be up to 30 min.5.10 Excess background noise may distort AE data or render the AE measurements useless. Users must be aware of the following common sources of background noise: (measurable flow noise); mechanical contact with the vessel by objects; electromagnetic interference (EMI) from cranes, and radio frequency interference (RFI) from nearby broadcasting facilities and from other sources; leaks at pipe or hose connections, or rain drops. This practice should not be used if background noise cannot be eliminated or controlled.5.11 Other Non-destructive test methods may be used to evaluate the significance of AE sources. Magnetic particle, ultrasonic, and radiographic examinations have been used to establish circumferential position, depth, and dimensions of flaws that produce AE. Procedures for using other NDT nethods are beyond the scope of this practice.1.1 This practice is no longer being updated but is being retained for historical value due to the procedures herein that are unique to the AE community.1.2 This practice provides guidelines for carrying out acoustic emission (AE) examinations of Yankee and Steam Heated Paper Dryers (SHPD) of the type to make tissue, paper, and paperboard products.1.3 This practice requires pressurization to levels used during normal operation. The pressurization medium may be high temperature steam, air, or gas. The dryer is also subjected to significant stresses during the heating up and cooling down periods of operation. Acoustic Emission data maybe collected during these time periods but this testing is beyond the scope of this document.1.4 The AE measurements are used to detect, as well as, localize emission sources. Other methods of nondestructive testing (NDT) may be used to further evaluate the significance of acoustic emission sources.1.5 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 / 折扣价： 502 元 加购物车

定价： 345元 / 折扣价： 294 元 加购物车

This specification covers electrically insulating, unbleached sulfate paper and paperboard used as layer insulation in coils, transformers, and other similar apparatus. The materials may also be used as turn insulation, slot liners, wedges, phase insulation, and separator papers in stranded wire/cable constructions. This specification does not include tissue for manufacture of capacitors. Other commonly used terms for the materials include soft coil wrap, dense coil wrap, kraft coil insulation, dry-finished kraft, and water-finished kraft. The materials covered in this specification are classified into four types according to density range and nominal thickness and should conform to the required values of ash content, alcohol-soluble material content, aqueous extract conductivity, water-soluble chloride content, fiber composition, moisture content, hydrogen ion concentration, pH, tensile strength, dielectric breakdown voltage, and conducting paths.1.1 This specification covers electrical grade unsized, unbleached sulfate paper and paperboard for use as layer insulation in coils, transformers, and similar apparatus. Other applications include, but are not limited to, turn insulation, slot liners, wedges, phase insulation, and separator papers in stranded wire/cable constructions. Tissue for the manufacture of capacitors is not included in this specification. Other commonly used designations include:1.1.1 Soft Coil Wrap,1.1.2 Dense Coil Wrap,1.1.3 Kraft Coil Insulation,1.1.4 Dry-Finished Kraft, and1.1.5 Water-Finished Kraft.1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 515元 / 折扣价： 438 元 加购物车

5.1 This test method provides a means of automatically separating and collecting atmospheric particulate and acidic gaseous fluoride samples.5.2 Since the samples are collected on dry tapes, the samples are in a form which allows elution of the fluoride content with a small volume of eluent. Consequently, the method allows analyses of air samples taken for a time period as short as several minutes.1.1 This test method describes the automatic separation and collection on chemically treated paper tapes of particulate and gaseous forms of acidic fluorides in the atmosphere by means of a double paper tape sampler. The sampler may be programmed to collect and store individual air samples obtained over time periods from several minutes to 3 h. A 30.5-m (100-ft) tape will allow unattended operation for the automatic collection of up to 600 samples.1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are included for information only and are not considered standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 / 折扣价： 502 元 加购物车

5.1 Paper machine rolls can range in size from 2.4 to 9 m [8 to 30 ft] long, with a shell thickness of from 12.5 to 75 mm [0.5 to 3 in.,] and 300 to 1200 mm [12 to 48 in.] diameter. Depending on purpose, paper machine rolls can weigh as little as 60 000 kg [13 000 lb] to as much as 27 500 kg [60 000 lb].5.2 If indications are found during this procedure it can be repeated, with additional sensors to refine source location accuracy.5.3 Removal of rolls for traditional NDT examination may be impractical and may not be sensitive enough to locate small defects.5.4 Traditional AE examination, whereby the roll is subjected to load greater than service load to detect crack extension, risks damage to the roll and is best employed as a follow-up NDT examination.5.5 Manual rotation through a full revolution subjects existing cracks to tensile and compressive forces which can open and close existing cracks, and cause friction at the crack surfaces.5.6 Excess background noise (overhead cranes, nearby maintenance activities) may distort AE data or render it useless. Users must be aware of the following common sources of background noise: bearing noise (lack of lubrication, spalling, and so forth), mechanical contact with the roll by other objects, electromagnetic interference (EMI) and radio frequency interference (RFI) from nearby broadcasting facilities and from other sources. This practice should not be used if background noise cannot be eliminated or controlled.5.7 Other Non-destructive test methods may be used to evaluate the significance of AE indications. Traditional AE has been used to confirm the existence of the AE indication and fine tune the location. Magnetic particle, ultrasonic and radiographic examinations have been used to establish the position, depth and dimensions of the indication. Procedures for using other NDT methods are beyond the scope of this practice.1.1 This practice provides guidelines for acoustic emission (AE) examinations of non-pressure, paper machine rolls.1.2 This practice utilizes a slow rotation of the roll to produce a full load cycle where load is provided by the weight of the roll suspended from its bearings or other journal support mechanism(s).1.3 This practice is used for detection of cracks and other discontinuities in rolls that produce frictional acoustic emission during rotation.1.4 The AE measurements are used to detect or locate emission sources, or both. Other nondestructive test (NDT) methods must be used to evaluate the significance of AE sources. Procedures for other NDT techniques are beyond the scope of this practice. See Note 1.NOTE 1: Traditional AE examination, magnetic particle examination, shear wave ultrasonic examination, and radiography are commonly used to establish the exact position and dimensions of flaws that produce AE.1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 8.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 / 折扣价： 502 元 加购物车

4.1 The folding endurance is frequently used to estimate the ability of the paper and plastics film to withstand repeated bending, folding, and creasing.4.2 Folding endurance has also been found useful in measuring the deterioration of paper and plastics film upon aging.1.1 This test method describes the use of the M.I.T.-type folding apparatus for determining folding endurance of paper and plastics film. The M.I.T. tester can be adjusted for samples of any thickness; however, if the outer layers thicker than about 0.25 mm (0.01 in.) rupture during the first few folds, the test loses its significance. The procedure for the Schopper-type apparatus is given in Test Method D643.1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 515元 / 折扣价： 438 元 加购物车