Case Study: Mechanical and Fabrication Works on Solid Feeders
Project Summary
Our team was contracted to carry out critical mechanical and structural refurbishment works on two solid feeders integral to the feedstock handling system of a high-throughput Anaerobic Digestion (AD) facility. The existing units were suffering from corrosion and structural degradation due to prolonged exposure to aggressive feedstock materials and inadequate previous repairs. The project scope involved full replacement of floor plates, renewal of internal wear elements, and fabrication of new structural elements along with hydraulic ram replacements to restore long-term integrity and operational reliability.
Client: Gravel Pit Biogas
Location: United Kingdom
Date of completion: 22/05/2025
Duration: 2 weeks
Contract Value: £35k
Contract Type: Lump Sum - Fixed Scope
Scope of works
Condition Assessment:
Pre-start inspections and visual survey.
Assessment of internal wear patterns and stress points around the floor and support beam interface.
Mechanical & Fabrication Works:
Full isolation and lock-out of the feeders from power and hydraulic systems.
Removal of old floor and wall components, including thrust plates, reinforcement angles, and fasteners.
Replacement of floor supports, including box-section bearers and cross-members fabricated off-site to exact dimensions.
Structural Improvements:
Reinforcement of vertical support legs using gusseted steel plates.
Installation of anti-corrosion treatment system (cold galvanising spray + industrial epoxy coating).
Introduction of drain points with self-cleaning ports to minimise fluid retention.
Testing & Commissioning:
Dry run testing of feeder augers to verify alignment.
Torque checks and bolt tension verification.
Handover with commissioning sign-off and O&M documentation.
Challenges
Corrosion had compromised safe access
Floor plate tolerances varied between feeders
Time-sensitive work to avoid process downtime
Removal of floors thrust plates given size and weight
Challenges & Solutions
Solution
Temporary support frames and mobile platforms were used to create safe zones
Templating used to ensure precision fit
Parallel working crews used to reduce project duration by 30%
Removal and reinstatement of existing precast walls
Outcomes
Improved Equipment Integrity: Structural life of feeders extended by an estimated 8–10 years.
Enhanced Operational Efficiency: Reduced downtime risk due to improved reliability of the feed system.
Health & Safety Compliance: Access upgrades ensure safer maintenance practices.
Client Satisfaction: Project completed on time, within budget, and with zero incidents.
Key Learnings
Early involvement in design and assessment phases enables more robust planning and fewer surprises.
Off-site fabrication and pre-assembly can significantly compress site time and reduce disruption.
Investing in higher-grade wear materials offers longer-term savings despite initial cost.
“Just a shout out for Chris and the Biocontractors team for their work over the last two weeks. Pleasure to have them on site. Really good attitudes from all of them, keeping us informed of progress and leaving the worksite tidy after job completion. Great on the H&S side too- paperwork spot on and toolbox talks carried out before work each day. “
John Fitzpatrick
Site Supervisor