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Port Pirie Smelter Transformation - Sulphuric Acid Plant Construction

Acid Plant Construction

Client: Nyrstar
Location: Port Pirie South Australia
Port Pirie Smelter Transformation - Sulphuric Acid Plant Construction

Scope of Works


Fabrication and Construction Management of the Acid Plant Ducting and Associated Structure.


Client / Owners: Nyrstar- Port Pirie CMT

3D Surveyors: Veris Australia- Melbourne

Primary Fabricator: Ottoway Engineering , Whyalla and Adelaide

SMP Installation Labour Contractor: Downer EDI Engineering

Insulation and Cladding Contractor: AIM     


For  6 (Six) ) months this element of the project was the major focus of the redevelopment and was on the Critical Path , with extensive time pressure being applied by senior and executive management locally, and from Europe .

A number of major fabrication and construction challenges were inherited when we commenced our role as Construction Superintendents. With allot of perseverance , collaboration and team work all challenges were eventually overcome, with all Ducts large and small diameter successfully installed.

The foot print size the plant sits within is very compressed which made the fabrication and installation of the large Ducting Design complex and prone to construction risk.

We were fortunate to have Downer EDI Engineering as the major SMP Construction Contractor assigned to this scope of work. Their leader ship team was extremely focussed and their commitment to safety was second to none.

The spirit of construction contracting, communication and cooperation was excellent and some of the best we have experienced in the past 25 years.

As always it’s the workforce who make these projects come together and complete the physical work.

The team we managed were extremely well lead, highly skilled tradesman and specialist in their field.

Despite all the time pressure and construction challenges involved, the end result was a successful and safe installation process.

    Project Specifics for Port Pirie Smelter Transformation - Sulphuric Acid Plant Construction

    Fast Facts

    The Sulphuric Acid Plant (SAP) is located downstream of the WGCP. It is designed to produce 1,000 ton per day of 98.5% sulphuric acid. SAP utilises double conversion and double absorption (3+1) technology.

    Major SAP equipment includes

    1.Drying Tower

    2.Intermediate Absorption Tower

    3.Final Absorption Tower


    5.SO2 Blower

    SMP Equipment Fabricated and Installed

    In total, approximately

    • 35 Individual Duct / Pipe Lines installed, including all associated mechanical equipment.
    • 500 lineal meters of insulated and clad Stainless Steel Pipe.
    • 75+ individual Crane lifts.
    • Weight 650 tonne

    3D Surveys, Virtual Fabrication and Installation Integration

    3D Surveys proved to be extremely valuable and a reliable source of truth and accuracy during the fabrication and installation of the ducting.

    The ducting interface nozzles and associated structural support steel were 3D surveyed and intergrated with the virtual construction model to determine the ‘As Built’ locations and prove that the ducting would align accurately during installation, and be free of any clashes with the associated structural steel and mechanical equipment.

    The 3D data was issued to the fabricator in easily interpreted marked up model screen shots.

    The modelled survey information was relied on over and above the isometric spool drawing to determine the fabrication of each duct.

    Following the completion of fabrication and prior to welding a 3D Survey was carried out on each duct in the workshop.

    Some of duct lines consisted of a number of spools that were collectively surveyed.

    The ‘As Fabricated’ survey information was integrated with the construction model for a complete virtual reassembly simulation of the complete duct line.

    All dimensional anomalies were corrected to enable the welding out of each duct.

    This process proved to offer an extremely accurate site interface, alignment and fit up with limited issues and clashes encountered.

    The accuracy from this process ensured that the expensive site labour and equipment was productive during construction with marginal down time assigned to modifications and rework.

    Safety risks were also significantly mitigated having the duct work fabricated accurately.

    Fabrication, Insulation and Cladding

    Due to the compressed program the fabrication, insulation and cladding was expedited at two (2) workshops located in Adelaide and Whyalla.

    The Ducting spools were free issued to the fabricator along with 3D Survey Data and Isometric Drawings.

    Both fabrication workshops worked 2 x 10 hour shifts on a seven day per week basis until the final ducting was completed.

    Insulation and cladding of the ducting was undertaken in the workshops on the same shift basis.

    The lagging companies rolling and cutting equipment was set up next to the ducting enabling an efficient materials flow and work to continue unimpeded.

    The decision to install the insulation and cladding in the controlled workshop environment resulted in the following advantages to the project,

    1.Consistently high quality standard.

    2.Expedited Construction Program.

    3.Limited down time. The production was not affected by adverse weather conditions, restrictive site access or competing with other trade works.

    4.Safe work environment. Clear access to avoid working at heights on site.

    5.Reduced men on site and at the Construction Camp.


    Ø Several oversize loads that consisted of police and piloted escorts were transported to site from Whyalla and Adelaide.

    Ø 14 days notice period was required for the police escorted loads. The fabricated equipment needed to be completed by the planned date to ensure the permit was valid and the load could be transported as planned.

    Ø All Ducting had specially designed lifting lugs that were located at positions made practical for loading on and off transport and other specifically designed lugs located for the final lift into position.


    At the peak of construction 90 (ninety) productive resources were assigned to this element of project.

    Three (3) crews rotated on a 3 week on 1 week off roster.

    At any one time;

    Ø One crew was assigned to a 10 hour day shift 7 days per week

    Ø One crew was assigned to a 10 hour night shift 7 days per week.

    Ø The 3rd crew was rotated out on R&R

    The productive resources were made up of the following trades and management


    2. Leading Hands

    3. Scaffolders (Intermediate and Senior)

    4. Pipe Fitters

    5. Certified Welders

    6. Mechanical Fitters

    7. Trades Assistants

    8. Insulators and Cladders

    9. Crane Drivers


    Three (3) Cranes were assigned to the Duct Install namely

    1. 180 Tonne 777 Manitowoc Crawler Crane

    2. 250 Tonne 999 Manitowoc Crawler Crane

    3. 250 Tonne Mobile Hydraulic Crane

    Ø A number of complex dual crane lifts were involved that required detailed lift studies and safe work method statements were prepared well in advance of the lifts.

    Ø Detailed planning and sequencing of Duct installation was critical to ensure the most practical and safe construction was achieved.

    Ø All major lifts were undertaken on day shift, with final ducting fit up and welding being completed primarily on night shifts.

    Ø All lifts were completed safely and without incident.


    The scale and significance of Scaffolding on this project was enormous.

    The scaffolding was required to facilitate access to the following tasks

    1. Initial Duct installation and fit up

    2. Welding out of the Duct

    3. Completion of the Insulation and Cladding

    At numerous locations up to 3 different Scaffolding configurations were required that involved

    1. Initial scaffold build.

    2. Scaffold reconfigure

    3. Scaffold dismantle

    4. Scaffold rebuild etc.

    An extremely high level of coordination was required to enable efficient workflows to continue.