BOP系统案例研究 -- 高压高精度变送器

产品：H455T2-33-P15-A1型压力变送器
说明：采用薄膜技术的高压H455型号，30K psi范围，HiP HF4或AE FC250等效工艺连接，HART 通信协议

问题：

防喷器（BOP）的原始设备制造商必须遵守API规范Q1中规定的内部质量标准，此外，许多制造商还制定了符合API S-53建议的重新认证计划，以翻新旧设备。Barksdale与一家BOP原始设备制造商（OEM）合作，该制造商致力于提供持续改进的质量管理体系，强调缺陷预防和测试产品的一致性，减少过程中的可变性和浪费。客户的校准计划要求对所有用于测试BOP系统的压力变送器进行90天周期的校准，目标是将校准精度保持在0.25%以内。如果无法保持准确度，则需要重新测试BOP系统，而OEM的成本非常高。OEM使用0.25%精度、30000 psi和10000 psi范围的4-20mA模拟变送器，使用箔应变计技术和电位计进行零点和量程微调。电位计是OEM在发现其超出精度规格时调整校准的重要功能。然而，电位计随温度和振动而漂移，这需要使用glyptol来防止旋转。OEM为每个变送器遵循严格的多点校准程序，如果需要调整电位计进行零点或量程微调，则可能需要四小时，甚至八小时。当变送器不能再在规范范围内校准时，将其丢弃。虽然原始设备制造商维护了一些备件，但替换变送器的供应商提供的交货期为14-22周。

解决方案：

经过多年的努力，Barksdale的新BiT产品系列为发射机找到了另一个能够在测试环境中生存并保持精度的来源，从而迎接了挑战。Barksdale的智能变送器的薄膜技术设计提供了更好的精度，可降至0.1%，并在高循环工业应用中证明了长期稳定性，可超过10亿次循环。此外，HART。通信协议为几个问题提供了一些显著的优点，并减少了定位和跟踪需要校准的发射机所花费的时间。

结果：

OEM对Barksdale变送器进行了疲劳、冲击载荷和低温/高温测试，随后进行了严格的校准过程，以确保校准得以维持。更高的精度提供了更多的裕度，以保持其最小0.25%的精度，并且预期更好的长期稳定性将增加微调之间的时间。HART协议允许数字零点微调和重新调整量程，从而消除了对随温度和振动漂移的电位计的需求，从而进一步提高了变送器的稳定性。BiT HART变送器量程调整功能包括10:1的调低，这允许OEM储存一个可从30000 psi或10000 psi范围重新配置的部件。HART协议的其他优点包括独特的设备ID和创建自定义标签以识别每个变送器的能力，以帮助跟踪和识别系统中变送器的物理位置。OEM能够在其现有数据采集系统中添加一个模块，通过HART协议进行通信，并从控制系统中识别安装在每个测试间中的变送器。

图1。显示带有数字零点微调和重新调整范围的BiT（左），以及带有电位计的竞争对手单元，用于手动调整零点和量程微调（右下）。电位计随温度和振动而漂移，需要glyptal将电位计锁定到位（右上）。

图2:显示防喷器测试间。测试包括在压力和冲击载荷下对橡胶密封插件进行高温和低温测试，在大型陆上防喷器上，包括立即施加0至7500 psi的压力。

Barksdale成立于1949年，是高度工程化控制产品的领先制造商。作为Crane Co.的子公司，Barksdale在仪表领域拥有领先的品牌地位，专注于通用工业、石油天然气和运输终端市场。凭借专有技术，Barksdale的阀门、调节器、压力开关、电子设备和速度仪表产品在苛刻的应用中为自己创造了一席之地。

Barksdale是防喷器阀门和调节器的领先供应商，还提供可用于满足API RP 53防喷器现场测试要求的危险区域BiT变送器。Barksdale保持流行车型的库存，以将交付周期缩短至最多4周。

BOP System Case Study

High pressure, high accuracy transmitter

Product: Model H455T2-33-P15-A1 Pressure Transmitter
Description: High Pressure H455 model with thin-film technology, 30K psi range with HiP HF4 or AE FC250 equivalent process connection, and HART? communication protocol

Problem:

Original equipment manufacturers of Blowout Preventer (BOP) are required to follow their internal quality standards per API specification Q1, in addition many have recertification programs that follow API S-53 recommendations to refurbish used equipment. Barksdale collaborated with a BOP original equipment manufacturer (OEM) that is committed to a quality management system that provides continuous improvement, emphasizing defect prevention and conformity of the product being tested with reduction of variability and waste in the process. The customer’s calibration program requires a 90-day cycle of all pressure transmitters used for testing their BOP systems with the goal of maintaining calibration within 0.25% accuracy. Failure to maintain accuracy requires retesting of BOP systems at a very high cost to the OEM. The OEM was using 0.25% accuracy, 30,000 psi and 10,000 psi range 4-20mA analog transmitters using foil strain gage technology with potentiometers for Zero and Span trim. The potentiometers were an important feature to the OEM to make adjustments to the calibration when they were found to be out of accuracy specification. However, potentiometers drift with temperature and vibration which requires application of glyptol to prevent rotation. The OEM follows a rigorous multi-point calibration procedure for each transmitter that can take up to four hours and potentially up to eight hours if any adjustment of the potentiometers for zero or span trim is required. When the transmitter can no longer be calibrated within specification, it is discarded. While the OEM maintained some spares, replacement transmitters had a 14-22 weeks lead time from their supplier.

Solution:

After years of trying to find another source for transmitters that would survive the testing environment and maintain accuracy, Barksdale’s new BiT product family met the challenge. Barksdale’s Intelligent Transmitter’s thin-film technology design provides better accuracy, down to 0.1%, and long term stability proven in high cycle industrial applications to over a billion cycles. In addition, HART. communication protocol provides some remarkable advantages to several problems and a reduction in time spent locating and tracking transmitters that were up for calibration.

Result:

The OEM put the Barksdale transmitters through a fatigue, shock loading and low/high temperature testing followed by their rigorous calibration process to ensure calibration is maintained. The higher accuracy provided more margin to maintain their minimum 0.25% accuracy, and better long term stability is expected to increase time between trim adjustments. HART protocol allows for digital zero trim and re-ranging to adjust span, eliminating the need for potentiometers that drift with temperature and vibration which further improves the stability of the transmitter. BiT HART transmitter re-ranging capability includes 10:1 turn down which allows the OEM to stock one part that can be reconfigured from 30,000 psi or 10,000 psi range. Additional benefits of HART protocol include the unique device ID and ability to create custom tags to identify each transmitter to help track and identify the physical location of the transmitter in a system. The OEM was able to add a module to their existing data acquisition system to communicate through HART protocol and identify transmitters installed in each test bay from the control system.

Figure 1.
Shows BiT with digital zero trim and re-ranging (Left), and competitors unit with potentiometers to manually adjust zero and span trim (Right Lower). Potentiometers drift with temperature and vibration and require glyptal to lock potentiometers in place (Upper right).

Figure 2.
Shows a BOP test bay. Testing includes high and low temperature testing of the rubber sealing inserts under pressure and shock loading, on large land BOP this included instant application of pressure from 0 to 7,500 psi.

Barksdale, founded in 1949, is a leading manufacturer of highly engineered control products. As a subsidiary of Crane Co., Barksdale has a leading brand position in instrumentation, with focus on General Industrial, Oil & Gas and Transportation end markets. With proprietary technologies, Barksdale’s valves, regulators, pressure switches, electronics, and speed instrumentation products have carved a niche for themselves in demanding applications.

Barksdale is a leading provider of valves and regulators for BOP’s and also provides hazardous area BiT transmitters that can be used to meet API RP 53 BOP testing requirements in the field. Barksdale maintains inventory for popular models to reduce lead time to maximum of 4 weeks.

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