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சி. எஸ். ஐ. ஆர். - கட்டமைப்பு பொறியியல் ஆராய்ச்சி நடுவம்

सीएसआईआर - संरचनात्मक अभियांत्रिकी अनुसंधान केन्द्र

CSIR - Structural Engineering Research Centre

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Fatigue & Fracture

Ratcheting studies on stainless steel straight pipes and elbows under combined internal pressure and cyclic bending (Sponsor: Bhabha Atomic Research Centre, Mumbai)

Ratcheting studies were carried out on SA 312 Type 304LN stainless steel straight pipes and elbows of 168 mm outer diameter under internal pressure and cyclic bending load. The internal pressure was varied between 25 MPa and 45 MPa in the case of straight pipes and 27.6 MPa and 39.2 MPa in the case of elbows. The specimens were filled with water and pressurized. Cyclic bending load was applied on the specimens by subjecting them to different levels of load-line displacement.

English

Cyclic Pressure and Burst Pressure Studies on API 5L X46 Grade Pipes (Sponsor: M/s. Hindustan Petroleum Corporation Limited, Mumbai)

M/s. Hindustan Petroleum Corporation Limited, Mumbai is having a large network of pipelines across the country for supply of petroleum. The pipeline of 14″ (API 5L X46 Grade steel) outer diameter and 162 km long (Mumbai-Pune Pipe Line) was commissioned in the year 1985. The pipeline was originally designed to operate at a pressure of 92 kg/cm2. Since inception, the pipeline has failed six times in the longitudinal weld seam while in operation during the years 1986 to 2014. The operating pressure was initially reduced to 80 kg/cm2 and then to 52 kg/cm2.

English

Studies on Fuel Drop Tank of Tejas under Slosh and Vibration Loadings (Sponsor: Aeronautical Development Agency, Bengaluru)

The Aeronautical Development Agency (ADA), Bengaluru has designed and developed the Light Combat Aircraft (LCA) - Tejas, for the Indian Air Force, with Hindustan Aeronautics Limited (HAL) as the Principal Partner and with other agencies including CSIR.  The 1200 litres fuel drop tank of Tejas (5 m long and 640 mm diameter) needs to be qualified for slosh and vibration loadings simultaneously as a mandatory requirement.

English

Fatigue and fracture studies on carbon and stainless steel pipe welds and elbows

Experimental investigations were carried out on 168 mm and 324 mm outer diameter pipes and elbows made of SA 333 Gr. 6 carbon steel and Type 304LN stainless steel used in power plant industry to demonstrate the Leak-Before-Break (LBB) design criterion.

English

Pipe fracture studies under compliant bending

Fracture studies were carried out on 18 numbers of 219 mm diameter of SA 333 Gr. 6 carbon steel straight pipes and elbows having through-wall crack under four point bending. The investigations have shown that the load carrying capacity of the pipes under finite compliance (fixed end condition) increases when compared to infinite compliance (simply supported condition).

English

Fracture studies on carbon steel pipes and elbows at high pressure and temperature subjected to bending moment

Fracture studies were carried out on 219 mm, 406 mm and 610 mm outer diameter of SA 333 Gr.6 carbon steel straight pipes and elbows having part-through/through-wall crack with internal pressure under in-plane bending.  The nominal thickness of the pipes and elbows varied 18.5 mm to 56.6 mm.  The initial notch angle varied from 30° to 150° and the internal pressure was maintained in the range of 10 MPa to 25 MPa.

English

Studies on ratcheting behaviour of pressurised pipes and elbows

Ratcheting studies were carried out on SA 312 Type 304LN stainless steel straight pipes (8Nos.) and elbows (4 Nos.) subjected to steady internal pressure and cyclic bending load. The internal pressure for all the straight pipes was ranging from 25 MPa to 45 MPa and in the case of elbows the internal pressure was varied for different elbows, ranging from 27.6 MPa to 39.2 MPa. Cyclic bending load was applied on the specimens by subjecting them to different levels of load-line displacement.

English

Bimetallic/narrow gap welded pipe fracture tests under cyclic bending load

In order to study the crack growth and cyclic tearing instability, which are required for realistic assessment of Leak Before Break applicability, experimental investigations were carried out on five numbers of narrow gap welded SA 312 Gr. TP 304LN stainless steel straight pipes of 324 mm outer diameter under quasi-cyclic loading. The pipe specimens which were tested under load control failed by ductile tearing till sufficient crack length was reached followed by sudden rupture and collapse.

English

Fracture behaviour of cruciform specimens under uni-axial and bi-axial bending at room and subzero temperature

Fracture studies were carried out on 135 mm thick notched cruciform specimens (20Mn 1Mo Ni55 steel) under uniaxial and biaxial bending at room and sub-zero temperature.  In the case of specimens tested under sub-zero temperature, a low temperature chamber was fixed at the centre of the cruciform specimen.  Liquid nitrogen was used to bring down the temperature to -70˚C at the core of the specimen and it was maintained throughout the test.  The test was conducted under load control.  Initial crack profile, profile after fatigue pre-cracking and final crack profile

English