Dhammika Welhenge received his initial training at the Ceylon Petroleum Corporation Sapugaskanda refinery and graduated as a Chemical & Process Engineer in 1979 from the University of Moratuwa. He received the corporate membership of the Institution of Engineers Sri Lanka (Chartered Engineer) in 1985.
After a short period working as a Chemical Engineer in the National Salt Corporation and National Engineering Research & Development Centre, he joined the State Fertilizer Manufacturing Corporation as the Shift Superintendent Ammonia plant. In SFMC, he was involved in the operation of Ammonia/Urea Plant from 1979 and was engaged in process plant commissioning, de-bottlenecking, operation, maintenance, start-ups, shutdowns, trouble shooting, etc and finally became the Plant manager and lead the decommissioning and mothballing activities in 1988. Government decided to close the Ammonia / Urea project in 1988.
Immediately after the closure of SFMC, he was offered the post of the Factory manager of the Sulphuric acid / Alum plant Ranala. During his tenure, he managed to optimize the operation and by 1990, manufacturing Sulphuric acid through DCDA process was made profitable and the plant was running at zero atmospheric emissions. He joined Unilever Sri Lanka as a Process Engineer in 1991 and served as the plant manager Toilet Soaps followed by Plant manager Edible Oil Refinery. He was appointed as the Country Safety Health & Environment Coordinator for Unilever Sri Lanka in 1994. He has been trained as an Accredited Safety Program Auditor by DNV. He was also appointed as a Regional SHE auditor for Unilever PLC Asia / Pacific region in 1996. He also received training as an EMS auditor in UK 1996 and EMS auditor Netherlands in 2000. He was trained and licensed by Du Pont as a Behaviour Based Safety trainer. While working as the SHE coordinator, he has been appointed as the Chief Engineer in 2006.
He took over the position of Country Health Safety & Environment Advisor for Shell Gas Lanka Limited in 2009. HSE management covered the LPG terminal (CBM), LPG filling plant and road transport. The Shell LPG business in Sri Lanka was divested in 2010 and taken over by the Government.
Throughout his career, while practicing as a Chemical & Process engineer, he worked as a visiting lecturer in the department of Chemical & Process Engineering, University of Moratuwa (from 1980 to 2009). he has also joined the faculty as a Senior Lecturer in 1990 and also worked as the Director, Industrial Training in 2009. He has served as the Chairman Chemical Engineering Section of the Institution of Engineers Sri Lanka three times from 1985 to date. He was the Executive Secretary of the Institution of Engineers Sri Lanka in 2008. He serves as a member of the ISO 14001 Environmental Management System advisory committee of the Sri Lanka Standards Institution and a member of the Sri Lanka Responsible Care Council. Dhammika serves as an external faculty member of Institute of Lean Management since 2015. Currently he is attached to the Laugfs Gas PLC as the General Manager HSE.