Senior AFT Impulse / CAESAR II Engineer – Supertall Concrete Pipeline Safety Audit

We are seeking an experienced Mechanical / Piping / Hydraulic Engineer to perform a technical safety audit and engineering analysis for a high-pressure concrete pumping pipeline serving a supertall structure with delivery elevations up to approximately 1,000 m.

This is a specialist engineering assignment. Applicants should have proven experience in hydraulic transient analysis, non-Newtonian/slurry pipeline modelling, high-pressure piping systems, and pipe stress / anchor reaction analysis.

Project Scope

The required study includes:

1. Hydraulic Pressure-Drop Profiling

Develop a complete hydraulic model of the concrete pumping system and calculate the pressure requirements and pressure-drop profile for the following vertical delivery zones:

400 m
700 m
1,000 m

The model shall consider, as applicable:

hydrostatic pressure;
straight-pipe friction losses;
elbows, bends, reducers and fittings;
pipe diameter changes;
concrete density;
concrete rheological properties;
non-Newtonian flow behaviour;
operating concrete flow rate.

Required outputs include:

pressure versus elevation profile;
pressure loss by pipeline section;
required pump discharge pressure;
operating velocity and flow;
governing pressure condition for each delivery elevation.
2. Primary Elbow Reaction Forces

Calculate the maximum vector hydraulic reaction forces acting on the primary horizontal elbow joints.

Required results:

Fx
Fy
Fz
resultant force

The analysis shall include pressure and momentum effects and shall report both steady-state and governing transient forces.

The coordinate system and force directions shall be clearly defined.

3. Dynamic Transient / Shock-Wave Analysis

Perform hydraulic transient analysis of the pumping system.

Minimum cases to be considered:

normal pumping;
pump startup;
normal shutdown;
sudden / emergency pump trip;
one additional credible governing transient event, if identified.

Required outputs include:

pressure versus time;
maximum transient pressure;
minimum transient pressure;
pressure-wave propagation;
governing transient event;
transient forces at critical elbows;
force time-history data required for pipe stress analysis.

The engineer shall clearly document assumptions relating to:

wave speed;
pipe-wall flexibility;
concrete compressibility;
damping;
non-Newtonian transient behaviour.

4. Intermediate Vertical Riser Anchor Loads

Develop the required piping stress / structural model to determine loads transferred to the intermediate riser anchor locations at:

Level 100
Level 167
Level 250

For each location, provide:

Fx
Fy
Fz
Mx
My
Mz

The analysis shall consider where applicable:

pipe self-weight;
contained concrete weight;
internal pressure;
pressure thrust;
transient hydraulic loads;
piping flexibility;
support / restraint configuration;
friction;
support stiffness;
temperature effects;
imposed movements where applicable.

The governing load combination shall be identified for each anchor.

The scope is limited to determining pipeline loads transferred to the building structure. Detailed reinforced-concrete wall design is not included.

5. 60 MPa Dynamic Pressure Wall-Thickness Safety Assessment

Assess pipeline wall-thickness adequacy for dynamic operating pressures up to 60 MPa.

The assessment shall consider:

pipe outside diameter;
nominal wall thickness;
steel material grade;
yield strength;
ultimate tensile strength;
manufacturing tolerance;
abrasive wear;
effective remaining wall thickness;
transient pressure;
appropriate engineering safety factors.

Required outputs should include, where technically justified:

nominal required wall thickness;
effective wall thickness;
minimum allowable remaining wall thickness;
recommended rejection / inspection thickness;
safety factor against yielding;
safety factor against ultimate failure.

Both new-pipe and worn-pipe conditions should be considered where sufficient information is available.

6. Pump Operating-Envelope Validation

Where complete SANY pump manufacturer data are provided, verify that the proposed pump can operate against the calculated system resistance.

The analysis shall identify:

required operating pressure and flow;
available pressure margin;
achievable flow at critical elevations;
compliance with manufacturer pressure and power limits.
Preferred Software

Preferred tools include:

AFT Impulse for hydraulic and transient analysis;
AutoPIPE Advanced or CAESAR II for piping stress and anchor reaction analysis;
Mathcad / Excel for independent engineering checks;
ANSYS only if local FEA is demonstrated to be necessary.

Equivalent professional software may be proposed, but the applicant must explain the methodology.

Required Deliverables

The successful engineer shall provide:

Design Basis / Assumptions Register.
Hydraulic model and input-data summary.
Pressure profiles for 400 m, 700 m and 1,000 m.
Pressure-versus-elevation plots.
elbow steady-state force calculations.
Full transient-analysis results.
Maximum/minimum transient pressure envelopes.
transient force results / histories.
Anchor reaction tables for Levels 100, 167 and 250.
60 MPa wall-thickness safety assessment.
Pump operating-envelope assessment.
Independent calculation sheets.
Native/editable hydraulic model files.
Native/editable pipe-stress model files.
Relevant raw results and exported data.
Final engineering report in editable Word format and PDF.
One technical model-handover / review meeting.
Important Requirements

Applicants should have demonstrated experience in at least several of the following:

AFT Impulse;
hydraulic transient / surge analysis;
non-Newtonian flow;
slurry, paste or concrete pumping systems;
Bingham Plastic / Herschel-Bulkley modelling;
high-pressure piping;
AutoPIPE or CAESAR II;
dynamic pipe stress analysis;
pipe support and anchor reaction calculations;
high-rise / vertical riser systems.

This is not a simple CAD or drafting assignment.

Please do not apply if your experience is limited only to piping layout or general mechanical design.

When Applying

Please provide:

brief summary of relevant experience;
software you propose to use;
examples of similar hydraulic transient, slurry, high-pressure piping or pipe-stress work;
your proposed engineering methodology;
estimated schedule;
fixed-price quotation or clearly defined milestone pricing;
confirmation that native/editable model files will be provided.

Please also answer the following technical questions:

How would you represent fresh concrete in a 1,000 m pumping pipeline: Bingham Plastic, Herschel-Bulkley, or another approach, and why?
How would you validate the predicted concrete pressure loss?
How would you calculate the hydraulic vector forces at a 90-degree elbow?
How would you model a sudden pump trip and determine the governing transient pressure?
How would you transfer transient hydraulic forces into a piping stress model?
What load components would you consider at an intermediate vertical riser anchor?
How would you establish a minimum safe / rejection wall thickness for a pipeline operating under transient pressures up to 60 MPa?

Preference will be given to engineers who provide technically specific answers rather than generic proposals.

Proposed Contract Structure

The work is expected to be awarded in milestones:

Milestone 1: Design basis and steady-state hydraulic model.

Milestone 2: B3 force analysis and transient / shock-wave analysis.

Milestone 3: Pipe-stress model and anchor reactions at Levels 100, 167 and 250.

Milestone 4: 60 MPa wall-thickness assessment, final report, native model files and technical handover.

Project data, drawings, pump information and available concrete / pipe specifications will be provided to the selected engineer.

Confidentiality and professional handling of project information are required.