December half revenue was up 71.4% to a record A$302.3 million, while EBITDA rose to $24.3 million from $14.2 million a year earlier.

Net profit after tax was up 72.7% to $14.7 million.

GR said project execution levels were higher during the half, with multiple project completions expected during the 2022 calendar year.

The company closed 2021 with cash of $93.6 million, up from $69 million six months earlier.

The company declared a half-year dividend of 9c per share, fully franked, up from 5c in the previous corresponding period.

Based on a strong order book, GR lifted full-year revenue guidance from $540-560 million to $580-600 million.

GR managing director Geoff Jones said the half-year results were pleasing.

"The operational performance has been solid as GR Engineering has safely and successfully progressed the work on multiple projects across a broad mix of commodities during HY22," he said.

"During the period, GR Engineering has successfully increased its pipeline of ongoing and near-term prospective projects which has resulted in increased visibility in revenue and earnings for FY23 and in future years."

Jones said the tight labour market had not impacted the company's margins and it continued to increase its workforce to meet demand.

"The business also continues to navigate through the impact of COVID-19 and has been able to manage equipment deliveries in line with project schedules despite delays with international shipping," he said.

"Whilst providing challenges, the commitment and response of the team across the business has been excellent."

GR shares opened 0.5% higher at $2.09.