Costain Group PLC
Graduate Mechanical Engineer

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Job Description
The Mechanical Engineering Department delivers mechanical & HVAC engineering scope for consultancy / operational delivery / design projects within multi-discipline engineering teams based in Costain’s Manchester office, primarily in the Natural Resources Division of Costain Group, in Water, Energy and Nuclear Sectors.
Typical Deliverables And Activities Include
- Specifications and Datasheets for Mechanical & HVAC Equipment
- Enquiry and Purchase Requisitions for Mechanical & HVAC Equipment Packages.
- Technical Bid Evaluations for Mechanical & HVAC Equipment Packages.
- Vendor design review for Mechanical & HVAC Equipment Packages.
- Factory Acceptance Testing for Mechanical & HVAC Equipment Packages.
- Process Flow Diagrams
- Ventilation Flow Diagrams
- Mechanical Flow Diagrams
- Mechanical Handling Diagrams
- Plant Layout
- Pumping system calculations and design
- Pressure Equipment calculations and design
- Mechanical Equipment calculations and design
- HVAC system calculations and design
To deliver the Engineering & Design Function within a specialist Mechanical Engineering Group, working primarily in the Natural Resources Division of Costain Group, in Water, Energy and Nuclear Sectors.
The job holder reports to the Chief Mechanical Engineer / Mechanical Engineering Discipline Lead.
It is expected that the job holder will generally be assigned to projects and therefore day to day reporting will be to project Lead Mechanical Engineer.
Costain offers a range of exciting development opportunities to accelerate your career and enable you to achieve your potential both during and after the Graduate Development Scheme.
This role will be based at either our Manchester office or London office. Please specify your preferred location on your job application. Please note, you may be required to visit different sites, so a full UK driving licence is essential.
Costain Graduate Development Programme
By joining our 2-year Graduate programme, you’ll get the best of both worlds—great technical development and exciting opportunities to grow your personal confidence and leadership skills. You’ll be working alongside your team to deliver standout, best-in-class projects across the infrastructure sector, all while learning and building your career step by step.
The Graduate Development Programme (GDP) is also a fantastic chance to meet and network with other graduates joining us at the same time. You’ll connect with people across different projects and disciplines throughout the UK, creating a supportive community from day one. Throughout the 2 years, you’ll come together both in person and virtually to take part in engaging modules and activities such as “Growing your Career,” “Costain In Action,” and “Group Coaching.” These sessions are designed to inspire you, challenge you in the best way, and help you get the most out of your programme.
Reasons to use Rodeo
I’m in my final year doing Economics and I don’t know whether to apply for grad schemes now or do a masters first. What do you think?
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Also worth knowing: most autumn 2026 applications are open now. Timing matters more than you think.
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Graduate Consultant — 2026 Scheme
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Why you're a good match
You’ve got the grades and the economics background, and your bank internship is exactly the experience this scheme looks for. Apply soon — deadlines close within the month.
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Your summer at the bank plus your econometrics coursework map directly to the day-one responsibilities on this scheme — client modelling, market briefings, and deal support.
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Your line manager will be fully on hand to support your learning, and you’ll have plenty of opportunities to talk through how you can put what you’re learning into your everyday work.
We also strongly recommend getting involved with our Graduate and Apprentice network (GRaAPs). It’s a brilliant way to meet other Early Careers members, discover what’s happening across different teams and projects, and explore areas of the business that genuinely interest you—helping you shape your future learning and direction.
And as a graduate, you’ll have the chance to help influence and shape future recruitment programmes and early careers opportunities—making a real difference to what comes next for future intakes.
Responsibilities
To comply with Company Policies, including
- Ethical business conduct Policy
- Health and Safety Policy
- ICT (Information & communication technology) acceptable usage Policy
- Information security & data protection Policy
- Quality Policy
To carry out design tasks delegated by the project Discipline Engineer or Engineering Manager
To be responsible for checking of design work in accordance with Company Procedures.
To liaise with other engineering disciplines as required
To provide support to Estimating, Proposals and Construction/Commissioning as required.
To be responsible for own development and training, by following the individual training programme and identifying opportunities for development.
Please note - In the above descriptions the term “design” is used in its broadest sense and covers design calculations, specifications, equipment selection and bid evaluation, requisitioning of equipment, approval of supplier’s documentation and provision of contract documentation.
Qualifications
Essential
- A Graduate Mechanical Engineer should be a degree qualified engineer aiming to develop in order to become an experienced engineer with broad experience as well as specialisms within a particular sector / discipline.
- An appropriate Degree, HNC, HND or equivalent in mechanical engineering or related discipline


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Desirable
- Experience in one or more of the following mechanical engineering fields:
- Energy
- Water
- Nuclear
- MEng Mechanical Engineering, Building Services, Water and Environmental Engineering or related discipline
- Aspiration to achieve Professional Qualification as a Chartered Engineer with IMechE, CIBSE or similar Institution.
About Us
Costain helps to improve people’s lives with integrated, leading edge, smart infrastructure solutions across the UK’s energy, water, transportation and defence markets. We help our clients improve their business performance by increasing capacity, improving customer service, safeguarding security, enhancing resilience, decarbonising and delivering increased efficiency. Our vision is to be the UK’s leading smart infrastructure solutions company. We will achieve this by focusing on blue chip clients whose major spending plans are underpinned by strategic national needs, regulatory commitments, legislation or essential performance requirements. We offer our clients leading edge solutions that are digitally optimised through the following five services which cover the whole lifecycle of their assets: future-shaping strategic consultancy; consultancy and advisory; digital technology solutions; asset optimisation and complex programme delivery. Our culture and values underpin everything we do.
Costain appreciate the time and effort taken when applying for one of our positions but, due to the high volume of responses, we are unable to provide individual feedback on candidates at application phase.
We do share individual feedback following an interview.
A Disability Confident employer will generally offer an interview to any applicant that disclose they have a disability and meets the minimum criteria for the job as defined by the employer.
It is important to note that in certain recruitment situations such as high-volume, seasonal and high-peak times, the employer may wish to limit the overall numbers of interviews offered to both disabled people and non-disabled people.
For more details please go to the Disability Confident website:
https://www.gov.uk/government/collections/disability-confident-campaign
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