Before the installation of the third vapor recovery equipment, a qualified foundation is essential. While the foundation may seem simple, it is actually the foundation for the smooth operation of the equipment throughout its entire lifecycle: if the foundation is uneven, the equipment feet will be unevenly stressed, leading to vibration and noise; if the foundation elevation is incorrect, the recovery pipeline will have to be manually adjusted, and the stress from the pipeline will be concentrated on the flange port, thus posing a leakage risk. In many cases handled on site, the root cause of the old problems such as "equipment shaking and joint leakage" can be traced back to the foundation not being solidly constructed back then. This article discusses how to construct the equipment foundation, what to inspect and accept, and how to remedy any issues that arise.
Why can't we be careless about equipment foundation
First, bearing capacity: The entire oil and gas recovery equipment, along with its operational dynamic load, concentrates its weight on a few machine feet. If the foundation's bearing capacity is insufficient or there is uneven settlement, it can lead to problems ranging from loose anchor bolts to deformation of the equipment body. Second, pipeline alignment: The elevation difference and horizontal position between the equipment's inlet and outlet and the recovery pipelines within the station must be precisely determined during foundation pouring. Forcing alignment of the pipelines later on can result in stress being trapped within the system. Third, environmental adaptability: The foundation in the oil and gas area should consider the surrounding drainage. If the top surface of the foundation is lower than or level with the ground, it is prone to water accumulation, which can lead to frost heaving in winter and perennial water immersion, both of which accelerate the deterioration of the foundation.
Five steps of foundation construction and acceptance
- Positioning and setting out: Determine the plane position and elevation benchmark according to the equipment foundation drawing, and verify that the equipment inlet and outlet orientations are consistent with the direction of the station's pipelines;
- Excavation and pouring: Determine the cushion and reinforcement practices according to the geological conditions. The concrete shall be poured and formed in one go, with the deviation of reserved anchor bolt holes or embedded parts controlled within the allowable range;
- Curing to strength: After pouring, it should be left undisturbed according to the curing requirements. It is strictly prohibited to lift and install equipment before the required strength is reached. Hasty completion to meet the construction schedule is a common cause of foundation cracking;
- Leveling in place: After the equipment is hoisted into place, use a level gauge to recheck at multiple measuring points on the skid. Adjust the machine feet by adding shims, and retighten the anchor bolts before conducting another recheck;
- Pipeline docking review: After connecting the pipes, review whether there is any additional stress on the inlet and outlet flanges. Only the ports that can align in a free state are qualified. Ports that are forced to align by bolts need to be reworked.
| Control link | What to do | Frequently Asked Questions |
|---|---|---|
| Positioning and setting out | Determine the position and elevation according to the foundation drawing, and verify the orientation of the pipe junction | If we only consider the width of the space and position ourselves accordingly, the pipelines may not align properly |
| Casting and reinforcement | Based on geological conditions, determine the cushion and reinforcement, and achieve one-time molding | Plain concrete is used for temporary support, which may lead to cracking and settlement in the future |
| Maintain until strong | Only when the strength is reached can one get on the equipment | To meet the tight deadline, the lifting was carried out ahead of schedule, causing damage to the foundation |
| In position and leveling | Multi-point horizontal verification, and adjustment of sizing blocks | Relying solely on visual inspection, hidden vibration hazards are overlooked |
| Pipeline docking | Align in a free state, without forced tension | Bolts are forcibly fitted to make up for the gap, leading to leakage from the flange |
| Document archiving | The records of setting out, strength, and leveling shall be included in the completion data | There will be no basis for future maintenance |
Judgment and remediation after foundation problems arise
If abnormal vibration occurs in operating equipment, anchor bolts repeatedly loosen, inlet and outlet flanges repeatedly leak, or the levelness of the skid exceeds the tolerance, the foundation can be suspected. The judgment method is as follows: After stopping the machine, measure the levelness of the skid and observe whether there are cracks on the foundation surface and whether there is water accumulation and sedimentation around the machine feet. Minor irregularities can be restored by adding pads for adjustment and tightening bolts; for obvious sedimentation or cracking, it is necessary to assess whether equipment relocation and foundation repair are required - this step is significant and must be carried out after a professional has provided a plan. For newly built stations, it is recommended to archive the foundation construction and acceptance materials (setting-out records, concrete strength reports, leveling records) along with the completion documents, which can be used for future equipment relocation or modification. If the foundation construction method is uncertain, provide the geological and layout information of the station area to Luoyang Wohong Petrochemical Equipment Co., Ltd. They can issue foundation construction requirements and embedded part drawings according to the equipment model, and cooperate with the civil engineering party to ensure a solid first step.
Frequently Asked Questions
How far in advance should the equipment foundation be constructed?
After concrete pouring, it needs to be cured until it reaches sufficient strength before equipment can be placed on it. This usually takes several weeks, and the specific timeframe is related to local temperature and construction methods. It is recommended to complete the foundation and allow sufficient curing time before the equipment arrives. Once the equipment is on site, it can be hoisted into place, so as not to delay the overall construction schedule due to waiting for the foundation.
Can skid-mounted equipment be placed directly without a foundation?
For small skid-mounted equipment placed on a reliable hardened ground, some can be positioned on the overall chassis, but it is necessary to calculate the ground bearing capacity and flatness, and to provide anti-displacement fixation. Whether a foundation is required should be confirmed in writing based on the equipment weight and the on-site ground conditions, rather than just placing it based on intuition.
Can the original foundation be utilized for the renovation of the old station?
First, do three things: verify whether the original foundation's plane dimensions match the anchor hole positions of the new equipment, inspect for cracks and settlement, and assess the elevation and alignment relationship with the new equipment's pipelines. If all three items pass the inspection, they can be utilized. If any one item fails, do not compromise and repair the foundation. Repairing the foundation is cheaper than operating it with defects.
This article is compiled by Luoyang Wohong Petrochemical Equipment Co., Ltd. The company provides design and manufacturing, skid-mounted customization, installation and commissioning, as well as after-sales operation and maintenance services for three-time oil and gas recovery equipment to gas stations and oil depots. If you need on-site inspection or scheme configuration, please feel free to contact us for discussion.