The full form of HVJ is Hajira-Vijaypur-Jagdishpur.

Explanation:
- HVJ refers to the Hazira-Vijaypur-Jagdishpur pipeline, which is a major natural gas pipeline in India.
- The pipeline is operated by GAIL (Gas Authority of India Limited), which is India's principal natural gas company.
- The pipeline runs from Hazira in Gujarat to Jagdishpur in Uttar Pradesh, covering a distance of approximately 1,670 kilometers.
- It is one of the longest and largest cross-country natural gas pipelines in the world.
- The pipeline was constructed to transport natural gas from the western offshore fields of Gujarat to various consuming centers in northern India.
- It plays a significant role in meeting the energy demands of industries, power plants, and households in the northern region of India.
- The pipeline has a capacity to transport around 33 million metric standard cubic meters per day (MMSCMD) of natural gas.
- It has multiple compressor stations along its route to maintain the pressure and ensure the smooth flow of gas.
- The pipeline has contributed to the growth and development of industries, particularly in the states of Uttar Pradesh, Bihar, Jharkhand, and West Bengal.
- It has also helped in reducing the dependence on other fossil fuels like coal and liquid fuels, leading to a cleaner and more sustainable energy mix.
- The HVJ pipeline has been a crucial infrastructure project in India's energy sector and has played a significant role in the development of the country's natural gas industry.

In conclusion, the full form of HVJ is Hajira-Vijaypur-Jagdishpur, which denotes a major natural gas pipeline in India operated by GAIL.