ASTM D1275 Standard Test Method for Corrosive Sulfar in Electrical Insulating Oil

Designati Desi gnation: on: D 1275 – 06

315/98

Standard Test Method for

Corrosive Sulfur in Electrical Insulating Oils 1 This standard is issued under the fixed designation D 1275; the number immediately following the designation indicates the year of  original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript supers cript epsilon (e) indicates an editorial change since the last revision or reapproval. This standard has been adopted for use by government agencies to replace Method 5328-2 of Federal Test Method Standard No. 791b. This standard was adopted as an ASTM-IP Standard.

1. Sco Scope pe

3. Summ Summary ary of Test Test Methods

1.1 This test method describes describes the detection detection of corr corrosive osive sulfurr compo sulfu compounds unds (both inor inorgani ganicc and orga organic) nic) in elec electric trical al insulating oils of petroleum origin. 1.2 New and in-se in-service rvice mineral mineral insulating insulating oils may conta contain in substances that cause corrosion under certain conditions of use. This test method is designed to detect the presence of, or the propensity to form, free (elemental) sulfur and corrosive sulfur compou com pounds nds by sub subjec jectin ting g cop copper per to con contac tactt wit with h oil und under er prescribed conditions. 1.3 Two met method hodss (A and B) hav havee bee been n int introd roduce uced d whe where re historically there has only been one. Method A is the one that has been in place since 1953. Method B is more rigorous and the preferred method. 1.4 The values values stated in SI units are to be regarded regarded as the standa sta ndard. rd. Inc Inch-p h-poun ound d uni units ts are inc includ luded ed for inf inform ormati ationa onall purposes. standard does not purpo purport rt to addr address ess the safet safetyy 1.5   This standard concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and  health practices and determine the applicability of regulatory limitations prior to use.

3.1  Method A—250 mL of oil is aged in a sealed flask for 19 h at 140°C in the presence of a copper strip. 3.2   Method B—220 mL of oil is aged in a sealed heavywalled bottle for 48 h at 150°C in the presence of a copper strip. This is the preferred method.

2. Referenced Documents 2.1   ASTM Standards: 2 D 130 Test Met Method hod for Cor Corros rosive ivenes nesss to Cop Copper per fro from m Petroleum Products by Copper Strip Test 2.2 Other Document: ANSI B74.10   Grading of Abrasive Microgrits 3

1

Thiss test method Thi method is und under er the jurisdicti jurisdiction on of ASTM Committee Committee D27 on Electrical Insulating Liquids and Gases and is the direct responsibility of Subcommittee D27.06 on Chemica Chemicall Te Test. st. Currentt editio Curren edition n approv approved ed March 1, 2006. Published March 2006 2006.. Origin Originally ally approved in 1953. Last previous edition approved in 2003 as D 1275 – 03. 2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@ [email protected] astm.org. g. For For Annual  Annual Book of ASTM   volume information, refer to the standard’s Document Summary page on Standards volume Standards the ASTM website website.. 3 Available Av ailable from American National Standards Institute, 25 W. 43rd St., 4th Floor, New York, NY 10036, USA.

4. Signi Significanc ficancee and Use 4.1 In most of thei theirr uses, insulating insulating oils are cont continual inually ly in contact with metals that are subject to corrosion. The presence of corrosive sulfur compounds will result in deterioration of  these metals. The extent of deterioration is dependent upon the quantity and type of corrosive agent and time and temperature factors. Detection of these undesirable impurities, even though not in terms of quantitative values, is a means for recognizing the hazard involved. 5. Appa Apparatus ratus 5.1   Bath—A hot-air oven or oil bath provided with suitable means of heating to, and controlling at 140 or 150 6  2°C. A circulating hot-air oven is preferred. 5.2   Flasks—Narr —Narrow-mo ow-mouth, uth, 250-m 250-mL, L, groun ground-gla d-glass ss stoppered flasks, of chemically resistant glass, capable of holding 270 to 280 mL when filled completely to the stopper. Flasks of  such capacity are required in order to allow sufficient space for expansion of the oil. 5.3   Bottles4—Heavy walled, 250 mL, bottles of chemically resist res istant ant gla glass ss con constr struct ucted ed wit with h nec necks ks to rec receiv eivee a PTF PTFE E threaded plug equipped with a fluoro-elastomer o-ring. Bottles of suc such h cap capaci acity ty and design design are required required in ord order er to all allow ow sufficient space for expansion of the oil and eliminate intrusion from atmospheric gases. 5.4  Copper Foil, 99.9+ % pure, 0.127 to 0.254 mm (0.005 to 0.010 in.) in thickness. 4 The sole source of supply of the bottles and PFTE screw plugs known to the committee at this time is Ace Glass, P.O. Box 688, Vineland, Vineland, NJ 08362, USA. If you are awar awaree of alte alternat rnative ive sup suppli pliers, ers, ple please ase pro provid videe thi thiss inf inform ormatio ation n to AST ASTM M International Intern ational Headquarters. Headquarters. Your Your commen comments ts will receive careful consideration consideration at a meeting of the responsible technical committee,1 which you may attend.

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D 1275 – 06 5.5   Polishing Material , consi consistin sting g of 240-g 240-grit rit silicon carbide paper or cloth, and also 230-mesh silicon carbide grains and pharmaceutical absorbent cotton. NOTE   1—It should be not noted ed tha thatt 240240-grit grit silicon silicon car carbide bide paper and 230-mesh silicon carbide grains have partic 230-mesh particle le sizes of about the same size (63 µm). In the United States, abrasive papers are classified in accordance with ANSI with  ANSI B74.10. B74.10.  Abrasive powders are classified by ASTM mesh size.

6. Reage Reagents nts 6.1   Acetone, cp. Nitrogen Gas—Comm 6.2   Nitrogen —Commerci ercial al cyli cylinders nders of nitr nitrogen ogen gas are satisfactory for this purpose. 7. Preparation of Apparatus 7.1 Chemical Chemically ly cle clean an flas flasks, ks, gla glass ss sto stoppe ppers, rs, bot bottle tless and PFTE screw plugs with solvents to remove oil, then wash the flasks with sulfur-free cleaning powder or liquid. Rinse with tap water, then with distilled water, and dry in an oven. 7.2 Cut a strip strip of copper copper 6 by 25 mm ( 1 ⁄ 4  by 1 in.) ( in.)  (Note Note 2) 2) and remove blemishes from surfaces with the 240-grit silicon carbide paper. Strips may be stored in sulfur-free acetone at this point poi nt for future future use. Do the final polishi polishing ng of the strip strip by removing it from the acetone, holding it in the fingers protected with wit h ash ashles lesss filt filter er pap paper er or nit nitril rilee glo gloves ves,, and rub rubbin bing g wit with h 230-mesh silicon carbide grains picked up from a glass plate with wi th a pa pad d of ab abso sorb rben entt co cott tton on mo mois iste tene ned d wi with th a dr drop op of  acetone. Wipe the strip with fresh pads of cotton and subsequently handle only with stainless steel forceps (do not touch with the fingers). Rub in the direction of the long axis of the strip. Clean all metal dust and abrasive from the strip, using successive clean cotton pads until a fresh pad remains unsoiled. Bend the clean strip in a V-shape at approximately a 60° angle and wash successively in acetone, distilled water, and acetone. Dry in an oven for 3 to 5 min at 80 to 100°C and immediately immerse the copper strip in the prepared test specimen of oil (Note 3). 3). Do not use compressed air or an inert gas to dry the copper strip. NOTE 2—It has been found convenient to polish a larger piece of copper from which, after the final polishing, several strips of the proper size may be cut. NOTE 3—This method of cleaning has been adapte adapted d from Test Method D 130. 130.

8. Met Method hod A 8.1 Use the oil to be tested as received. received. Do not filter the oil through paper. 8.2 Promptly Promptly place the pre prepar pared ed cop copper per strip in a cle clean an 250-mL flask to which has been added 250 mL of the oil to be tested. Place the bent copper strip standing on its long edge so that no flat surface lies along the glass bottom of the vessel. Lubricate the ground-glass stopper with a small amount of the test specimen. Bubble nitrogen through the oil in the flask by means of a glass tube connected to the reduction or needle valve of the cylinder (rubber connections must be sulfur-free) for 1 min, and quickly put the stopper loosely in place. 8.3 Place the stoppered stoppered flask (immersed (immersed to the neck in the event an oil bath is employed) in the oven at 140°C. When the oil in the flask has reached approximately 140°C, tighten the stopper more firmly (Note ( Note 4). 4). Remove the flask after heating

for 19 h  6  10 min at 140  6  2°C. Carefully take the copper strip from the flask and wash with acetone or other suitable solvent to remove all of the oil and let air dry. Do not use pressurized air to dry copper strip. NOTE  4—The corrosive effects of unstable sulfur compounds present in the oil are reduced when aged under strong oxidizing conditions such as when oxygen is present. It is imperative to keep the flask well sealed after nitrogen bubbling. If the oil visibly darkens during testing then most likely oxygen has entered the vessel and oxidized the oil. In these cases, the test procedure has become compromised and must be repeated.

8.4 To inspect, inspect, hold the test strip in such a manner that light light reflected reflect ed fro from m it at an ang angle le of app approx roxima imatel tely y 45° will be observed. 9. Met Method hod B 9.1 Prepa Prepare re the test specimen specimen as descr described ibed in 8.1 8.1.. 9.2 Promptly Promptly pla place ce the prepared prepared cop copper per strip in a cle clean an 250-mL bottle to which has been added 220 mL of the oil to be tested. Place the bent copper strip standing on its long edge so that no flat surface lies along the glass bottom of the vessel. 16 Bubble nitrogen through the oil in the bottle by means of a 1 ⁄ 16 in. inner diameter glass or stainless steel tube connected to the reduction or needle valve of the cylinder (rubber connections must be sulfur-free) for 5 min at a rate of 0.5 L/min. Quickly screw in the PFTE plug equipped with fluoro-elastomer o-ring. 9.3 Place the bottle bottle in the oven at 150°C. After After 15 min of  heating at 150°C, partially unscrew the PFTE plug to release the pressure and then screw it back down so the bottle does not burst. Remove the bottle after heating for 48 h  6  20 min at 150 6  2°C. Allow to cool. Carefully take the copper strip from the flask and wash with acetone or other suitable solvent to remove all of the oil and let air dry. Do not use pressurized air to dry copper strip. 9.4 To inspect, inspect, hold the test strip in such a manner that light light reflect refl ected ed fro from m it at an ang angle le of app approx roxima imatel tely y 45° will be observed. If a specimen is borderline or unclear, take a clean labora lab orator tory y tis tissue sue and dra drag g it acr across oss the sur surfac facee wit with h hea heavy vy pressu pre ssure; re; if any of the dep deposi osited ted mat materi erial al is rem remove oved, d, the deposit is corrosive and is to be reported as such. 10. Interpretatio Interpretation n of Results 10.1 Class Classify ify the oil as corrosive corrosive or nonco noncorros rrosive ive in acco accorrdance with Table with  Table 1. 1.  Classification of corrosive or noncorrosive is to be aided through the use of ASTM Copper Strip Corrosion Standards as referenced in Test Method  D 130. 130. A desc descripti ription on of  the tarnish levels is provided in  Table 2 for 2  for reference only. 11. Repor Reportt 11.1 Report the following information: information: 11.1.1 11 .1.1 Sampl Samplee ident identifica ification, tion, and TABLE TAB LE 1 Copper Strip Classifications Classifications Classification Noncorrosive Noncorrosi ve

Corros Cor rosive ive

Description Orange, red, Orange, red, lavender lavender,, multicol multicolored ored with with lavender lavender blue blue or silver, or both, overlaid on claret red, silvery, brassy or gold, magenta overcast on brassy strip, multicolored with red and green showing (peacock) but no gray Trans Tr anspar parent ent bla black, ck, dar dark k gray gray or dar dark k brow brown, n, gra graphi phite te or lusterless black, glossy or jet black, any degree of flaking

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D 1275 – 06 TABLE TAB LE 2 Copper Strip Tarnish Level Classifications Classifications Classi- Designation fication Freshly .. .... Polished Strip 1 Slight Sli ght tar tarnis nish h ... 2

Moderate tarnish ... .... ..

Description Unable Unab le to re repr prod oduc uce e up upon on ag agin ing g so no de desc scri ript ptio ion n is provided a. Lig Light ht ora orange nge,, alm almost ost th the e sam same e as fre freshl shly y pol polish ished ed strip b. Dark orange a. Claret red b. Lavender c. Mu Mult ltic icol olor ored ed wi with th la lave vend nder er bl blue ue or si silv lver er,, or bo both th,, overlaid on claret red d. Silvery e. Brassy or gold

... ... 3

Dark ta Dark tarn rnis ish h .... ..

a. Ma Mage gent nta a ov over erca cast st on br bras assy sy st stri rip p b. Mu Mult ltic icol olor ored ed wi with th re red d an and d gr gree een n sh show owin ing g (p (pea eaco cock ck), ), but no gray

4

Corr Co rros osio ion n

a. Tr Tran ansp spar aren entt bl blac ack, k, da dark rk gr gray ay or br brow own n wi with th pe peac acoc ock k green barely showing b. Gr ap aphite or lusterless black c. Glossy or jet black

... ...

11.1.2 Tes Testt specimen as being corrosive or noncorrosive, 11.1.3 Tar Tarnish nish level according to Test Method D Method  D 130, 130, and 11.1.4 11 .1.4 Metho Method d A or Method B. 12. Pre Precisi cision on and Bias 12.1 No statement is made about either either the precision or bias bias of this test method since the result merely states whether there is con confor forma mance nce to the criteria criteria for suc succes cesss spe specifi cified ed in the procedure and is not quantitative. 13. Keyw Keywords ords 13.1 corrosion; corrosive sulfur; elemental elemental sulfur; free sulfur; insulating; mineral; oils; petroleum; sulfur

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