The STEPS FOR DPT TEST IN TRUSS discuss in this post. The Dye Penetration Testing (DPT) is a test uses to identify, the discontinuities in welding joints and connections. And uses to detect the cracks, fractures, etc. It is a low cost inspection method known as the Liquid Penetrate Inspection ( LPI ), Dye Penetrant Inspection ( DPI ).
The Cleaner, the Penetrant and the Developer are the three main materials for this DPT testing. These are all the Non toxic chemicals. And Eco friendly materials. Using these Cleaner, the Penetrant and the Developer, the DPT testing carries out.
This Dye Penetration Testing has different names,
- Liquid Penetrate Inspection ( LPI )
- Dye Penetrant Inspection ( DPI )
- Penetration Testing ( PT )
It is a simple test. And easy test to identify the discontinuities in welding joints. Using this DPT TEST ON TRUSS MEMBERS all the surface defects and the flaws are easily identify and rectify. This test carries out without difficulties. This is one of the oldest test for identification of the defects in welding in truss joints and the connections.
STEPS FOR DPT TEST IN TRUSS
There are some important steps for DPT test in truss. This vary by the factors like, the applying system, the size and the components of materials. And the type of discontinuities, environment and the climatic conditions, etc,. The major steps of testing are,
- Surface Preparation
- Drying After cleaning
- Penetrant Application
- Penetrant Dwell
- Excess Penetrant Removal
- Developer Application
- Indication Development
The STEPS FOR DPT TEST IN TRUSS are as follows,
1. Surface Preparation
After completions of all the welding for joints and the connections of truss components, the welding slug removes. This performs using mechanical means or by chipping hammers. And cleans with a steel wire brush.
The Surface to examine cleans fully. All the adjacent sides of the welding joints cleans properly up to minimum of twenty centimetre. The joint coated with the primer and the paint removes with the paint remover, wire brush or by mechanical means for testing.
This performs to obtain the accurate results. It must be free from dirt, dust, paint, oil, grease, rust, and the other foreign materials. And cleans with the cleaner. The Cleaner is uses to clean the surface of welding joints and the connections of member. The specimen to test cleans for applying of the Penetrant in the welding joints.
2. Drying After Cleaning
After cleaning, the member allows to dry. This makes to form a dry and a clean surface for the testing. This takes three to five minutes depending on the condition of the site. And size of the material to test. This cleaning makes, if any residue of liquid presents on the member, it blocks the passing of the penetrant. This drying process carries with the help of hot air driers, air blowers, etc.
3. Penetrant Application
The Penetrant applies to the dry surface. This carries with brushing or spraying. For better, accurate and quick results, the spraying operations carries out.
It sprays exactly on the surface of members. And sprays exactly on the welding connections for examining of the flaws.
4. Penetrant Dwell
The penetrant remains on the surface for a sufficient time to passes into the defects. This dwell time is the total time that the penetrant is in contact with the surface. This varies depends upon the application method, the type of materials, etc,. The normal dwell time is three to five minutes. This depends on the size of materials, the length of welding joints.
5. Excess Penetrant Removal
After sufficient penetration, the excess penetrant all around the surface of material wipes off. And cleans in all the welding joints. This cleaning carries out with a dry clothes and clean wipers.
After removal of the excess penetrant, it allows to dry in normal temperature. No other drying methods like, drying with hot air driers, air blowers, etc requires. This penetrant allows to remain on the member for five to ten minutes. It depending on the size of materials and the length of welding joints. This makes the penetrant sink into the cracks, pores, holes, etc. This depends on the size of the welding joints and connections.
7. Developer Application
The Developer is a thin layer white in colour. It applies quickly on to the surface. And the welding joints, to examine on the truss members. This carries out with the spraying. The complete area of penetrant covers with spraying the Developer.
This application of developer carries out within one to two minutes after drying of the penetrant. This developer available in various forms like, dusting, dipping, spraying.
8. Indication Development
The developer allows to remain on the surface for a sufficient time period. This development time is a minimum of ten minutes. And the maximum time periods take place depending on tight cracks.
The Inspections performs after a minimum time period of ten minutes. And under necessary lighting to detect the indications from the defects, flaws.
The discontinuities in welding joints identifies. It is clearly visible on to the surface welding joints. And the cracks, fractures, pinholes, porosity, potholes, evaluates.