RU2597763C1 - Method of collecting samples for subsequent analysis of solid component of welding aerosol - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to sampling solid component of welding aerosol (TSSA) formed during arc welding, for subsequent analysis and can be used for collection and sampling of TSSA in various welding processes. Method involves collection of solid component of welding aerosol in breathing zone of welder using a sampling device wherein sampling is performed after welding arc ignition and generating directed airflow in respiratory zone of welder, sampling device for catching solid component of welding aerosol is carbon-bearing surface of double-sided carbon tape, which by sticky side is attached to mask of welder, and after welding process scotch tape is peeled from mask and placed in a container for subsequent analysis.

EFFECT: possibility of sampling in stationary and field conditions without using expensive equipment with low labour input.

3 cl, 3 dwg, 3 tbl, 1 ex

Description

The invention relates to the welding industry, and in particular to methods for capturing the solid component of the welding aerosol (TCCA) generated during arc welding. The method can be used for trapping and sampling TCCA during various welding processes, such as submerged arc welding, cored wire welding, carbon dioxide welding, and also in oxygen and plasma cutting of metals.

A known method of studying aerosol particles using transmission electron microscopy in order to obtain samples of natural and artificial TCCA deposited on a millipore filter (RU 1529071, publ. 15.12.1989). The filter is preliminarily impregnated (10-15%) with a nitrocellulose solution in amyl acetate or acetone, which leads to its dissolution, as a result of which the filter surface becomes dense and smooth after the solution has dried, which eliminates the carbon replica with extraction by spraying coal onto its surface particles, which can be further investigated by electron microscopy and microanalysis.

The disadvantage of this method is that the sampling is carried out by airborne sounding and is not intended to capture the smallest particles of TCCA.

Also known are sampling methods for collecting TCCA (ed. St. No. 559074, publ. 05/25/1977, RU 2185575, publ. 07/20/2002), the common disadvantages of which are that they are extremely stationary, time-consuming and require special equipment.

Closest to the claimed method is the selection of aerosol solid particles for subsequent determination of the mass concentration of metals and metalloids in the air of the working area using atomic emission spectrometry with inductively coupled plasma (ISO 15202-1: 2012 Workplace air - Determination of metals and metalloids in airborne particulate matter by inductively coupled plasma atomic emission spectrometry - Part 1: Sampling (Standard ISO 15202-1: 2012. Working air - Determination of solid particles of metals and metalloids in the air of the working area using inductively coupled atomic emission spectrometry zmoy - Part 1: Sampling), published June 1, 2012.

(http://www.iso.org/iso/catalogue_detail.htm?csnumber=51315)

According to the specified method, sampling is performed at the welder's workplace. Sampling area - the space around the welder’s face, sampling time: 8 hours for long-term measurements and 15 minutes for short-term measurements.

Particles are collected on a special sampling device by pumping a measured volume of air through a filter installed in the sampling device. The method is intended to determine the mass concentration of TCCA.

The disadvantage of this method is that it is exclusively stationary, time-consuming, because for sampling, it requires special equipment at the welder's workplace and is intended only to determine the mass concentration of TCCA.

The technical result consists in creating a sampling method for the subsequent analysis of TCCA, allowing sampling in the field without the use of expensive equipment with low labor intensity.

The essence of the invention lies in the fact that when implementing the sampling method for subsequent analysis of TCCA, including the capture of TCCA in the welder’s breathing zone using a sampling device, according to paragraph 1 of the formula, sampling is carried out after ignition of the welding arc and creating a directed air flow into the welder’s breathing zone The carbon-containing surface of double-sided carbon tape is used as a sampling device for catching TCCA, which is glued to the welder’s mask with the sticky side, and at the end Processes welding tape unstick from the mask and placed in a container for subsequent analysis.

In addition, in order to obtain more complete information about the characteristics of TCCA, the subsequent analysis of the sample includes the determination of the morphological, chemical and fractional compositions of TCCA using scanning electron scanning microscopy, photon correlation spectrometry and X-ray microprobe analyzer (paragraph 2 of the formula).

In the welding process use at least 5 electrodes (p. 3 formulas).

The choice of such a number of electrodes is based on the fact that during a visual inspection of the carbon-containing surface of the adhesive tape with a smaller number of electrodes, no significant adhesion of the welding aerosol particles was found.

The method used double-sided carbon tape produced by LLC TESKAN (Czech Republic), available on the website http://tescan.ru/products/bycategory/3/74/skotch-klej-kraska

One side of the adhesive tape is a layer of highly dispersed carbon (0.5-1.0 μm), applied to the adhesive base. Spectrometric analysis showed the presence of 91.81-94.02% carbon, the rest - oxygen, sodium and sulfur.

The lower side of the adhesive tape, as well as the adhesive base of the carbon-containing layer, are a sticky surface that is usually used in various adhesive tapes, for example, 3M brand (http://forum.xumuk.ru/index.php?showtopic=73868).

Solids of the welding aerosol are deposited on the carbon-containing surface of the adhesive tape and are held onto it by the adhesive base.

Creating a directed flow, for example, using local forced ventilation, provides a more uniform deposition of solid particles on the carbon-containing surface of the adhesive tape, increasing the reliability of further analysis of the deposited particles.

The ability to stick adhesive tape, peel it off after the welding process and store it in a container makes it possible to conduct subsequent analysis of the sample in special laboratory conditions, and not directly at the welder's workplace, which simplifies and reduces the cost of known sampling methods.

The invention is illustrated by the following figures.

In FIG. 1 shows a scheme for sampling TCCA according to the claimed method, where:

1 - welder mask;

2 - carbon tape;

3 - electrode;

4 - a metal plate;

5 - air flow;

6 - stream containing TCCA.

In FIG. 2 shows a micrograph of the carbon-containing surface of the tape. Spectrometric analysis showed the presence of 91.81-94.02% carbon, the rest is oxygen, sodium and sulfur, the dispersion of carbon particles is 0.5-1.0 μm.

In FIG. 3 - results of a morphological study of TCCA particles using 2 types of electrodes (1st column - LB-52U electrodes, 2nd column - OK 46.00 electrodes).

The implementation of the proposed method is presented in a specific example.

Example

The object of the study was the particles of the solid component of the welding aerosol, which are formed during manual arc welding on a plate of steel 20 with a thickness of 10 mm.

Two types of electrodes were used:

- Kobe Steel LB-52U with the main coating;

- ESAB OK 46.00 with rutile coating.

Diameter of electrodes d = 3 mm, welding current 90 A, welding rectifier VD-306. The number of electrodes is 5 pieces. The distance from the welding arc to the welder's mask is 300 mm.

A carbon-containing side was glued on top of the welder’s mask with a 6 mm tablet of double-sided carbon tape manufactured by TESKAN LLC, Czech Republic.

During welding, forced ventilation was carried out using a fan, creating a directed flow of air and aerosols.

The time for each welding operation averaged 10 minutes.

After the welding process was completed, the adhesive tape tablet was removed from the welder's mask and placed in a special container.

When interacting with oxygen, particles deposited on carbon tape can be oxidized, therefore, after sampling the particles, it was necessary to study the samples within 2 days.

Studies have shown the following results.

Particle morphology is shown in the photo in FIG. 3. By morphology, the particles were conditionally divided into 3 groups: spheres, agglomerates, and clusters.

In FIG. Figure 3 shows that after welding with Kobe Steel LB-52U electrodes with a basic coating, TCCA consists of agglomerates, spherical particles and clusters. When using electrodes ESAB OK 46.00 with a rutile coating - from spherical particles with a smooth surface.

Particle sizes were determined using scanning electron microscopy (SEM) using a high-resolution scanning electron microscope (3-10 nm, maximum magnification 300000X) S3400N from HITACHI (Japan).

The particle size was from 5 to 32 μm, as shown in table 1.

The study of the chemical composition of TCCA was carried out using x-ray microprobe analysis.

The research results are presented in tables 2, 3.

It is seen (Table 2) that the following chemical elements are present in the composition of TCCA: Fe, O, Na, Ca, Si, K, S, Al. Agglomerates contain O, Na, Si, S, Cl, K, Ca and Fe, spherical particles with a fibrous surface - Fe, O. Clusters are similar in chemical composition to agglomerates, because they contain O, Na, Al, Si, K. There is no carbon.

TCCA using electrodes OK 46.00 (Table 3) contains: agglomerates with clusters, which include O, Mg, Al, Si, F, S, Ca, Fe, Zn; spherical particles, including such elements as O, Na, Mg, Al, Si, K, Fe, and fibrous particles, consisting of the following chemical elements: O, Al, Si, Ca, Ti, Mn, Fe, no carbon.

Claims (3)

1. The method of sampling for subsequent analysis of the solid component of the welding aerosol, including the capture of the solid component of the welding aerosol in the welder’s breathing zone using a sampling device, characterized in that the sampling is carried out after ignition of the welding arc and creating a directed air flow into the welder’s breathing zone, sampling A device for trapping the solid component of the welding aerosol is the carbon-containing surface of double-sided carbon tape, which is sticky Rhone adhered to the welding mask, and after the welding process tape unstick from the mask and placed in a container for subsequent analysis. 2. The method according to p. 1, characterized in that the subsequent analysis of the sample includes determining the morphological, chemical and fractional compositions of TCCA using scanning electron scanning microscopy, photon correlation spectrometry and X-ray microprobe analyzer. 3. The method according to p. 3, characterized in that at least 5 electrodes are used in the welding process.

Images