1、Designation: D1998 06D1998 13Standard Specification forPolyethylene Upright Storage Tanks1This standard is issued under the fixed designation D1998; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numbe
2、r in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This specification covers flat-bottom, upright, cylindrical tanks molded in one-piece seamless construction by rotationalmolding. The tanks
3、 are molded from polyethylene for above ground, vertical installation and are capable of containing aggressivechemicals at atmospheric pressure. Included are requirements for materials, properties, design, construction, dimensions,tolerances, workmanship and appearance. Tank capacities are from 1900
4、 L 500 gal(500 gal) up.1.2 This specification does not cover the design of vessels intended for use at pressures other than atmospheric pressure.Furthermore, this specification does not cover the design of portable tanks. It is also not for vessels intended for use with liquidsheated above their fla
5、sh points, or temperatures above 66C 150F(150F) for Type I tanks and 60C 140F(140F) for TypeII tanks for continuous service. NFPA Standards 30 and 31 shall be consulted for installations that are subject to the requirementsof these standards.1.3 Special design considerations not covered in this spec
6、ification shall be given to vessels subject to superimposed mechanicalforces, such as seismic forces, wind load or agitation; to vessels subject to service temperature in excess of 23C 73.4F;(73.4F);and vessels subject to superimposed pressure exceeding 25.4 cm 10 in.(10 in.) of water or 2.5 103 MPa
7、 0.36 psi.(0.36 psi).1.4 The values stated in SI units are to be regarded as the standard. The values given in bracketsparentheses are for informationonly.NOTE 1There is no similar or equivalent ISO ISO 13341:2005+A1:2011 and ISO 13575:2012 are similar, but not equivalent to this standard.1.5 The fo
8、llowing precautionary caveat pertains only to the test methods portion, Section 11, of this specification: This standarddoes not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of thisstandard to establish appropriate safety and he
9、alth practices and determine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD883 Terminology Relating to PlasticsD1693 Test Method for Environmental Stress-Cracking of Ethylene PlasticsD2837 Test
10、Method for Obtaining Hydrostatic Design Basis for Thermoplastic Pipe Materials or Pressure Design Basis forThermoplastic Pipe ProductsD3892 Practice for Packaging/Packing of PlasticsD4703 Practice for Compression Molding Thermoplastic Materials into Test Specimens, Plaques, or SheetsE691 Practice fo
11、r Conducting an Interlaboratory Study to Determine the Precision of a Test MethodF412 Terminology Relating to Plastic Piping Systems2.2 OSHA Standard:29 CFR 1910.106 Occupational Safety and Health Administration, Flammable and Combustible Liquids32.3 ANSI Standard:B-16.5 Pipe Flanges and Flanged Fit
12、tings41 This specification is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.15 on Thermoplastic Materials(Section D20.15.01).Current edition approved Sept. 1, 2006Oct. 1, 2013. Published October 2006October 2013. Originally approved in
13、1991. Last previous edition approved in 20042006 asD1998 - 04.D1998 - 06. DOI: 10.1520/D1998-06.10.1520/D1998-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the
14、standards Document Summary page on the ASTM website.3 Available from Occupational Safety and Health Administration (OSHA), 200 Constitution Ave., NW, Washington, DC 20210.4 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036.This document is not
15、 an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate
16、. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.4
17、 NFPA Standards:30 Flammable and Combustible Liquid Code531 Installation of Oil Burning Equipment52.5 ISO Standards:6ISO 13341:2005+A1:2011 Static Thermoplastic Tanks for the Above Ground Storage of Chemicals Blow Moulded orRotationally Moulded Polyethylene Tanks Requirements and Test MethodsISO 135
18、75:2012 Static Thermoplastic Tanks for Above Ground Storage of Domestic Heating Oils, Kerosene and Diesel Fuels Blow Moulded and Rotationally Moulded Polyethylene Tanks and Rotationally Moulded Tanks Made of AnionicallyPolymerized Polyamide 6 Requirements and Test Methods3. Terminology3.1 Definition
19、s: DefinitionsDefinitions are in accordance with Terminologies D883 and F412 and the Association ofRotational Molders (ARM) Glossary of Terms,7 unless otherwise indicated.3.2 Definitions of Terms Specific to This Standard:3.2.1 impact failure, nany crack in the test specimen resulting from the impac
20、t and visible in normal room lighting to a personwith normal eyesight.3.2.2 rotational molding, na three-stage commercial process consisting of loading the mold with powdered resin, fusing theresin by heating while rotating the mold about more than one axis, and cooling and removing the molded artic
21、le.3.2.3 service factor, na number less than 1.0 (that takes into consideration all the variables and degrees of safety involved ina polyethylene storage tank installation) that is multiplied by the hydrostatic design basis to give the design hoop stress.4. Classification4.1 Tanks meeting this speci
22、fication are classified according to type as follows, and it is the responsibility of the purchaser tospecify Type I or Type II:4.1.1 Type ITanks molded from cross-linkable polyethylene.4.1.2 Type IITanks molded from non-cross-linkable polyethylene.5. Materials5.1 This specification is based upon th
23、e use of 100 % virgin polyethylene intended for the rotational molding process. Any useof regrind, recycled or reprocessed materials, or combinations of such materials, shall not rely upon the performance data of theiroriginal constituents, but must meet the requirements of this specification in its
24、 own right.5.1.1 The polyethylene shall have a stress-cracking resistance of 500 h minimum F50 in accordance with Test Method D1693,Condition A, full-strength stress-cracking agent. The test specimens shall be compression molded or rotational molded. Ifcompression molded, Procedure C of Annex A1 of
25、Practice D4703 shall be followed for both types of polyethylene with aminimum platen temperature of 177C 350F(350F) for Type II materials. The temperature for Type I (cross-linkable)polyethylene shall be 197C 390F(390F) and the platen shall be kept closed under full pressure for five minutes at the
26、specifiedtemperature in order to bring about the crosslinking reaction. If the test specimens are rotational molded, the conditions forrotational molding shall be similar to the conditions used for molding a tank from this polyethylene.NOTE 2The stress-cracking test is not used as an indicator of ge
27、neral chemical resistance of a polyethylene. Refer to the polyethylene suppliers ormolders chemical-resistance chart for information on the resistance of the polyethylene to specific chemicals or products, or test specific products orchemicals prior to use.5.2 All tanks used for outdoor installation
28、 shall contain an ultraviolet stabilizer at a level adequate to give protection for theintended service life of the tanks. This stabilizer shall be compounded into the polyethylene.5.3 Any pigments added must be compatible with the polyethylene and shall not exceed 0.5 % dry blended, and 2 %compound
29、ed in, of the total weight.NOTE 3The use of dry-blended pigments may have an effect on physical properties, that is, impact strength.5.4 Each resin used in designing tanks covered by this specification shall have hydrostatic-hoop-stress data available.6. Design Requirements for Both Type I and Type
30、II Tanks6.1 Cylinder Shell (Unsupported Portion of Tanks)The minimum required wall thickness of the cylindrical shell at any fluidlevel shall be determined by the following equation, but shall not be less than 4.7 mm 0.187 in.(0.187 in.) thick. The toleranceindicated in 9.1.2 applies to these dimens
31、ions.5 Available from National Fire Protection Association (NFPA), 1 Batterymarch Park, Quincy, MA 02269-9101.6 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.7 Available from Association of Rotational Molders, 2000 Spri
32、ng Road, Suite 511, Oak Brook, IL 60523.800 Roosevelt Road, C-312, Glen Ellyn, IL 60137, tel:630-942-6589.D1998 132T 5P 3OD/2 SD (1)where:T = wall thickness, mm in.,T = wall thickness, mm (in.),P = pressure, MPa (0.0098 MPa/m-H2O SG H(m), or psi (0.433 psi/ft-H2O SG H(ft),SG = specific gravity of fl
33、uid,H = fluid head, m ft,H = fluid head, m (ft),OD = outside diameter of tank, mm in., andOD = outside diameter of tank, mm (in.), andSD = hydrostatic design stress, MPa psi.SD = hydrostatic design stress, MPa (psi).6.1.1 The hydrostatic design stress that is used to determine the minimum wall thick
34、ness at any fluid level must be based onhoop stress data for the resin. The hoop stress data, obtained in accordance with the procedures of Test Method D2837, providea hydrostatic-design-basis for the resin. The hydrostatic-design-basis must be reduced by a service factor to determine the actualhydr
35、ostatic design stress. The maximum service factor shall be 0.5 for wall thicknesses less than 9.5 mm 0.375 in.(0.375 in.).For thicknesses equal to or greater than 9.5 mm 0.375 in.,(0.375 in.), the maximum service factor shall be 0.475. For example,if the hydrostatic-design-basis for the resin is 8.7
36、 MPa 1260 psi,(1260 psi), the hydrostatic design stress for a tank with wallthickness greater than 9.5 mm 0.375 in.(0.375 in.) is 0.475 8.7 = 4.1 MPa or(or 0.475 1260 = 600 psi.psi).6.1.2 Tank hoop stresses shall be derated for service above 23C 73.4F.(73.4F).6.2 Cylinder Shell (Externally Supported
37、 Tanks)The minimum required wall thickness for the cylinder straight shell must besufficient to support its own weight in an upright position without any external support, but shall not be less than 4.7 mm 0.187in.(0.187 in.) thick. The tolerance indicated in 9.1.2 applies to these dimensions.6.3 To
38、p HeadMust be integrally molded with the cylinder shell. The minimum thickness of the top head shall be equal to thetop of the straight wall.6.4 Bottom HeadMust be integrally molded with the cylinder shell. The minimum thickness for a full-supported flat-bottomhead shall be 4.7 mm 0.187 in.(0.187 in
39、.). The radius of the bottom knuckle of a flat-bottom tank shall not be less than 25.4 mm1 in.(1 in.) for tanks with a diameter less than 1.8 m 6 ft(6 ft) and 38.1 mm 1.5 in.(1.5 in.) for a diameter greater than 1.8m 6 ft.(6 ft). The minimum thickness of the radius shall not be less than the maximum
40、 thickness of the cylinder wall.6.5 Open-Top TanksThe top edge of open tanks shall be reinforced by design to maintain its shape after installation.7. Fittings7.1 Fabricated nozzles, gaskets, and other fitting accessories must be chemically compatible with the materials to be handledin the tanks.7.2
41、 Openings that are cut in tanks to install fittings must not have sharp corners. Holes shall have minimum clearance to insurebest performance of fittings.7.3 The size, location, and specification, and so forth, for manways and fittings shall be agreed upon between the purchaser andthe manufacturer.7
42、.4 The vents must comply with OSHA 1910.106 (F) (iii) (2) (IV) (9) normal venting for atmospheric tanks, or other acceptedstandard, or shall be at least as large as the filling or withdrawal connection, whichever is larger but in no case less than 25.4 mm1 in.(1 in.) nominal inside diameter.7.5 Fitt
43、ings installed in tanks shall be of appropriate strength to meet manufacturer and purchaser specifications.7.6 Bolts securing mechanical fittings must be manufactured of materials compatible with tank contents.7.7 Provisions shall be made to attach hold-down devices to the tanks for outdoor service.
44、7.8 For all flanged connectors, the flange drilling and bolting shall be in accordance with ANSI/ASME B-16.5 for 150 psi 1MPa(1 MPa) pressure class straddling the principal centerline of the vessel.8. Performance Requirements8.1 The following performance requirements shall be met by Type I and Type
45、II tanks:8.1.1 Low-Temperature ImpactLow-temperature impact shall be determined using the test method described in 11.3. Therequirements for Type I and Type II tanks are as follows:D1998 133Wall thickness, mm in. Impact energy,min. J ft-lbWall thickness, mm (in.) Impact energy,min. J (ft-lb)4.7 mm 0
46、.187 in. to and including 6.4 mm 0.25 in. 122.0 904.7 mm (0.187 in.) to and including 6.4 mm (0.25 in.) 122.0 (90)6.6 mm 0.26 in. to and including 12.9 mm 0.50 in. 135.5 1006.6 mm (0.26 in.) to and including 12.9 mm (0.50 in.) 135.5 (100)12.9 mm 0.51 in. to and including 19.3 mm 0.75 in. 203.2 15012
47、.9 mm (0.51 in.) to and including 19.3 mm (0.75 in.) 203.2 (150)19.3 mm 0.76 in. to and including 25.4 mm 1.00 in. 271.0 20019.3 mm (0.76 in.) to and including 25.4 mm (1.00 in.) 271.0 (200)Greater than 25.4 mm 1.00 in. 271.0 200Greater than 25.4 mm (1.00 in.) 271.0 (200)8.1.2 Percent Gel, for Type
48、I Tanks OnlyThe percent gel level shall be determined using the test method described in 11.4.The percent gel level for Type I tanks on the inside 3.2 mm 0.125 in.(0.125 in.) of the wall shall be a minimum of 60 %.9. Dimensions and Tolerances9.1 GeneralAll dimensions will be taken with the tank in t
49、he vertical position, unfilled. Tank dimensions will represent theexterior measurements.9.1.1 Outside DiameterThe tolerance for the outside diameter, including out of roundness, shall be 63 %.9.1.2 Shell Wall and Head ThicknessThe tolerance for average thickness at each elevation shall be 10 % of the designthickness on the low side and shall be unlimited on the high side. The tolerance for individual audit readings shall be lim
