During the fourth quarter of 2021, the company generated revenues of $161 million and adjusted consolidated EBITDA of $13.4 million representing sequential increases of 15% and 57%, respectively, despite global challenges associated with the COVID-19 pandemic, supply chain disruptions, and a modest seasonal decline in U.S. customer completion activity.
Highlighting our fourth quarter was a 34% sequential increase in our Offshore/Manufactured Products segment revenues, coupled with another quarter of strong orders booked into backlog yielding a 1.1 times book-to-bill ratio for the period and a full-year ratio of 1.2 times.
During the fourth quarter of 2021, the industry experienced a 9% sequential quarterly increase in the average U.S. frac spread count compared to the same period in 2020, the average U.S. frac spread count has doubled.
During the fourth quarter, we generated revenues of $161 million adjusted consolidated EBITDA of $13.4 million and a net loss of $19.9 million or $0.33 per share.
These quarterly results were burdened by a $9.3 million reclassification of unrealized foreign currency translation adjustments and $2.2 million of noncash inventory and fixed asset impairment charges due to the decision to exit certain nonperforming regions and service lines.
In addition, we recorded $0.8 million or $800,000 of severance and restructuring charges in the quarter.
Excluding these charges, our adjusted net loss was $0.14 per share.
We ended the year with $53 million of cash on hand, compared to $68 million at the end of the third quarter.
The quarterly decrease in cash was attributable to a $24 million build in working capital, essentially all of which related to trade receivables associated with the sequential increase in revenues in our Offshore/Manufactured Products segment.
As of December 31, no borrowings were outstanding under our asset-based revolving credit facility and amounts available to be drawn totaled $49 million, which, together with cash on hand, resulting in available liquidity of $102 million.
At December 31, our net debt totaled $126 million, yielding a net debt-to-capitalization ratio of 15%.
We spent $6.5 million in capex during the fourth quarter, which was substantially offset by proceeds received from the sale of assets totaling $5.4 million.
In 2022, we expect to invest approximately $25 million to support the expected market expansion.
For the fourth quarter, our net interest expense totaled $2.6 million, of which $0.5 million was noncash amortization of debt issuance costs.
Our cash interest expense, as a percentage of average total debt outstanding, was approximately 5% in the fourth quarter.
In terms of our first quarter 2022 consolidated guidance, we expect depreciation and amortization expense to total $18.2 million, net interest expense to total $2.7 million, and our corporate expenses are projected to total $9.3 million.
Our Offshore/Manufactured Products segment reported revenues of $92 million and adjusted segment EBITDA of $13.7 million in the fourth quarter of 2021, compared to revenues of $69 million and adjusted segment EBITDA of $8.6 million reported in the third quarter of 2021.
Segment revenues increased 34% sequentially, driven primarily by increases in project-driven and service revenues of 72% and 17%, respectively.
Adjusted segment EBITDA margin in the fourth quarter of 2021 was 15%, compared to 12% in the third quarter of 2021.
Backlog totaled $260 million as of year-end, a 4% sequential increase culminating in our highest backlog level achieved since the first quarter of 2020.
Fourth quarter 2021 bookings totaled $105 million yielding a quarterly book-to-bill ratio of 1.1 times and a year-to-date ratio of 1.2 times.
During the fourth quarter, we booked one notable project award exceeding $10 million.
Approximately 11% of our fourth quarter bookings were tied to non-oil and gas projects, bringing our full-year non-oil and gas bookings to 10%.
For nearly 80 years, our Offshore/Manufactured Products segment has endeavored to develop leading-edge technologies, while cultivating the specific expertise required for working in highly technical deepwater and offshore environments.
In our Well Site Services segment, we generated revenues of $43 million in the fourth quarter of 2021, and adjusted segment EBITDA increased sequentially to $6.2 million, excluding severance and restructuring charges in the comparable periods.
Adjusted segment EBITDA margin in the fourth quarter of 2021 increased to 14%, compared to 13% reported in the third quarter of 2021.
During the most recent quarter, we made a strategic decision to exit certain nonperforming service offerings within this segment, resulting in $2.2 million in noncash inventory and fixed asset impairment charges and $300,000 in severance and restructuring charges.
In our Downhole Technologies segment, we reported revenues of $26 million and adjusted segment EBITDA of $0.1 million in the fourth quarter of 2021, compared to revenues of $26 million in adjusted segment EBITDA of $1.4 million reported in the third quarter of 2021.
We expect 2022 full-year consolidated EBITDA to range from $60 million to $70 million with roughly 60% of the total generated in the second half of 2022.
crude oil inventories have now drawn down considerably with expanding economic activity, leaving the U.S. at 411.5 million barrels in inventory as of February 11, which was about 10% below the five-year range.
Crude oil prices have responded with spot WTI crude oil over $90 per barrel, setting up a very favorable outlook for 2022.

Summary:
During the fourth quarter, we generated revenues of $161 million adjusted consolidated EBITDA of $13.4 million and a net loss of $19.9 million or $0.33 per share.
Excluding these charges, our adjusted net loss was $0.14 per share.