GOST 21639.1-90

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  ГОСТ 21639.1-90

GOST 21639.1−90 Fluxes for electroslag remelting. Methods for determination of moisture content

GOST 21639.1−90

Group B09

STATE STANDARD OF THE USSR

FLUXES FOR ELECTROSLAG REMELTING

Methods for determination of moisture content

Fluxes for electroslag remelting.
Methods for determination of moisture content

AXTU 0809

Valid from 01.07.92
before 01.07.97*
_______________________________
* Expiration removed by Protocol No. 7−95
The interstate Council for standardization,
Metrology and certification (I & C N 11, 1995). -
Note the manufacturer’s database.

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of heavy machine building of the USSR

DEVELOPERS

P. L. Babushkin, V. Y. Persits, PhD. chem. Sciences; Y. A. Margolin; M. P. Gerashchenko, V. A. of the chair (supervisor); Zelenova, O. B.; O. A. Raspopin; N. D. Vishniac

2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee on management of quality and standards from 29.12.90 N 3472

3. REPLACE GOST 21639.1−76

4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

This standard specifies gravimetric methods for determination of hygroscopic moisture in the mass fraction of from 0.5 to 5.0% and total moisture for the mass concentration of from 0.01 to 5.0% in fluxes for electroslag remelting.

1. GENERAL REQUIREMENTS

General requirements for methods of analysis GOST 21639.0*.
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* Valid GOST 21639.0−93. — Note the manufacturer’s database.

2. METHOD OF DETERMINATION OF HYGROSCOPIC MOISTURE

2.1. The essence of the method

The method is based on drying of the sample flux at a temperature of 105−110 °C to constant weight.

2.2. Equipment

Analytical scale with weights.

Drying oven electrically heated and thermostat.

Cups for weighing (buxy) according to GOST 25336.

Desiccator, according to GOST 25336 filled with calcium chloride for NTD.

2.3. Analysis

A portion of the flux weight of 20−50 g was placed in buxu, pre-dried at 105−110 °C to constant weight and weighed with lid.

Then bucsu a hitch and the cover removed is dried in a drying Cabinet at 105−110 °C for 2 h, covered with a lid, cooled in a desiccator and weighed 30−40 minutes.

Before weighing cover buxy slightly open to equalize the pressure and quickly closed. Repeat drying for 30 minutes to constant weight. If re-weighting is an increase in mass, the final result of taking a lot prior to its increase.

2.4. Processing of the results

2.4.1. Mass fraction of hygroscopic moisture () in percent is calculated by the formula

,

where is the mass of buxy with the suspension before drying, g;

 — weight boxy a hitch after drying, g;

 — the weight of the portion,

2.4.2. Allowable absolute differences of the results of the parallel definitions should not exceed the values given in table.1.

Table 1

3. METHOD FOR THE DETERMINATION OF TOTAL MOISTURE

3.1. The essence of the method

The method is based on heating of the analyte in a tube furnace at a temperature of 1000 °C in flowing oxygen, turning the contained hydrogen in the moisture and its gravimetric determination after absorption of magnesium perchlorate (angerona). To reduce the error of analysis of the evolved gaseous compounds of fluorine are absorbed by the lead monoxide at the exit of the tube.

3.2. Apparatus, reagents and solutions

Setup for determination of moisture (Fig.1) consists of the oxygen cylinder (1) according to GOST 5583, equipped with a pressure reducing valve start-up and adjustment of a current of oxygen; reducer pressure gauge (2) — fine adjustment of oxygen; safety bulb (3), which in case of overpressure in the combustion chamber prevents the ingress of sulfuric acid in the rubber tubing connecting the device with a reducing valve; the system of cleaning and drying of oxygen, rinsing the flask (4) with sulfuric acid; drying columns (5) and (6), filled with granulated sodium hydroxide and magnesium perchlorate; a porcelain tube (7) length of 500 mm and an inner diameter of 20−25 mm; tube furnaces (8) brand SUOL-0.25.1/12-M1; asbestos tube (9), saturated with lead monoxide, heated to a temperature of 800 °C. copper tube (10) heated to a temperature of 110−120 °C; an l-shaped pipe (11); the absorption flasks (12) with magnesium perchlorate (angerona). L-shaped pipeline made of austenitic stainless steel and consists of two symmetrical separable parts, the total length of the pipeline is 750 mm. the Spiral heater is placed around and along the curved profile of the pipeline copper pipe while also isolating the heater turns of asbestos cord CHAON-3 impregnated with liquid glass. A tube with a heater braid tape made of PTFE and placed in the lower part of the housing pipeline, pre-lined with kaolin wool, top up with the heater also cover the kaolin wool and covers the upper part of the housing pipeline. Both parts of the case fasten with screws through the holes in the ears welded to the upper and lower parts of the pipeline.

Damn.1

Permitted heaters and absorption flasks other structures providing the required accuracy of the analysis.

The hook with which the boat was placed in a tube and extracted from it, is made of heat-resistant wire with a diameter of 3−5 mm and a length of 400−600 mm.

To install the tube in a porcelain tube using a special pusher with the catch.

Laboratory scales for General purpose according to GOST 24104*, not lower than 2nd accuracy class with the largest weighing limit of 200 g or other scales that meets the specified requirements for their metrological characteristics.
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* On the territory of the Russian Federation GOST 24104−2001, here and hereafter. — Note the manufacturer’s database.

To determine the mass fraction from 0.01 to 0.03% use laboratory scales for General purpose according to GOST 24104 is not below 1st class of accuracy.

Sulfuric acid according to GOST 4204.

Sodium hydroxide according to GOST 4328.

Of magnesium perchlorate on the other 6−09−3880.

Kaolin wool or asbestos fiber on the other 6−09−4010.

Lead monoxide (II) on the other 6−09−5382.

3.3. Preparation for assay

Pour in the rinse flask (4) 125 cmof sulfuric acid. Drying columns (5) and (6), and the absorption flask (12) is prepared to work in accordance with the devil.2. The mass absorption flasks prepared in the form of (70±2) g. of magnesium Perchlorate should not asiatica tightly. Absorption flask with a diameter of 30 mm in the lower part 5−6 holes with a diameter of (1±0,2) mm Height of the absorption bulb 105 mm.

1 — glass wool; 2 — absorber; 3 — glass wool

Damn.2

In calcined along the entire length of the porcelain tube is placed a tube, impregnated with lead monoxide. Tube (9) from long-fibre asbestos or kaolin wool, pre-calcined at 400 °C for 30 min, prepared as follows: a steel brush pour a uniform layer of fibrous asbestos or kaolin wool and evenly cover the asbestos co-lead. By rubbing two steel brushes provide uniform distribution of monoxide lead asbestos. The excess of lead monoxide shake sieve. For impregnation of 100 g of asbestos requires about 100 g of monoxide of lead. 4,5−5,0 g impregnated asbestos (kaolin wool) is sufficient for the formation of the tube. Both sides of the tube are placed glass wool 10 mm on each side (Fig.3).

Damn.3

The constancy of oxygen consumption is determined by the rotameter (2), which is installed in front of the safety bulb. The flow of oxygen through the system occurs at a rate of 175−225 cm/min.

Before starting, heat the oven to a temperature of 1000 °C and check the installation for leaks. For this connect instead of the absorption of the bulb (12) glass tube, the end of which dipped into a Cup of water and interrupt the flow of oxygen, holding the hose in front of the safety bulb. If the water in the glass tube rises, the system is sealed.

The ends of helical heater located around and along the curved profile of the pipeline (11) copper tubes (10), connected to latro RNO-250−2 and set the voltage to the outlet temperature of the copper tube was 110−120 °C.

Porcelain boats N 2 — according to GOST 9147 or quartz boat (length of 100−120 mm, width 15−20 mm, height 10 mm) was calcined in flowing oxygen at a temperature of 1000 °C before operation.

Before starting, set the average value of the blank experience. After the furnace temperature reaches 1000 °C flow and oxygen consumption 175−225 cm/min, weighing of the absorption flask (12) every 5−7 min. Installation ready to use when the difference in weight between each weighing not more than 0.2−0.4 mg. the Value of the idle experience more than 0.4 mg demonstrates the need for prevention of the installation.

To do this, you must replace the reagents used for the dehydration of oxygen (sulfuric acid, sodium hydroxide and magnesium perchlorate) and to clean from contamination all parts of the installation.

Tube (9) provides a delay of fluorides for the total number of tests. Control over the operation of the tube is carried out by changing the color of perchlorate of magnesium in the absorption flask (12), caused by penetration of fluoride.

3.4. Analysis

Weighed samples of ground mounted depending on the mass fraction of moisture on the table.2, placed in a porcelain or quartz boat.

Table 2

A boat with a hook is introduced into the most heated portion of the porcelain tube (7) and tightly closed the tube with a rubber stopper through which passed a tube to supply oxygen. The moisture extracted from the sample is distilled in an absorption flask (12), while volatile side-products and fluoride are absorbed by the lead monoxide at the exit of the tube. The sample left in the furnace until, while in the upper part of the glass tube and absorption of the bulb (12) there will be condensation (no more than 5−7 minutes). Then seal the absorption flask (12), closing the upper hole tube and the lower hole for the output of the oxygen tight rubber ring and weighed. Remove analyzed sample from the oven, connect the absorption flask (12) to install and start analyzing the next sample.

3.5. Processing of the results

3.5.1. Mass fraction of moisture () in percent is calculated by the formula

,

where is the mass absorption flasks after analysis, g;

 — the mass of the same flask prior to analysis, g;

 — the weight of the portion of the flux to be analyzed,

3.5.2. Allowable absolute differences of the results of three parallel measurements at a confidence level =0.95 does not exceed the values given in table.3.

Table 3