泵体阀门壳体用改性PP，材料要长期泡在介质里、又长期承压——不是"耐得住"就够。这篇讲介质清单怎么列、加载状态下的耐化学判据、长期静液压的多温度外推、法兰蠕变松弛与验证顺序，并说明长期 90℃ 以上、强溶剂或高扬程场合为什么不该用改性PP硬撑。
有个做化工计量泵的工程师，拿一只裂开的泵壳来问："用了四个月，从法兰根部裂开，一掰就断。料检拉伸强度是合格的，是不是料有问题？"
我问三句话：介质是什么、多少度、压力多大。他答：自来水加一点除垢剂，六七十度，压力不高。
方向就这么定了——不是"强度不够"，是"长期在介质里、又被法兰螺栓一直拉着"，裂在应力最大的那一圈。
泵体、阀门壳体这类件，材料要长期在介质里、又长期承压。它得在这两件事同时在场的情况下"活着"，而不只是"耐得住"。
"耐得住"是短期泡一泡不变形；"活着"是几千小时后，法兰还在、密封面还在、螺栓预紧力还在。这两件事的验证方法完全不同。
一、泵阀件的失效现场：裂的不在流道，在应力最大那一圈
结论先说：这类件最常见的失效不是被压力顶爆，是从法兰根部、螺孔周边、圆角处裂开——位置几乎都指向"介质 + 应力"的组合。
现场一：法兰根部开裂，料检合格。 件用几个月，从法兰圆角放射状裂开，常规物性查不出问题——这是环境应力开裂：介质渗入诱发银纹，装配应力与预紧力把它拉开。短期浸泡看不出来，因为它没加载。
一个内行细节：同一款料、同一种介质，无应力试样泡 1000 小时可能毫无变化；加载到 1% 应变后，几百小时就出现银纹。只做无应力浸泡的报告，对承压件基本没有参考价值。
二、工况六维拆解：温度、内压、介质、寿命，数字先报齐
结论先说：六维里介质和温度是一票否决线；载荷维要拆成"内压"和"装配应力"两笔账。
| 维度 | 实际工况 | 对材料的要求 |
|---|
| 温度 | 常温循环水 20-40℃；热水与清洗工况 60-80℃，局部可到 90℃ 以上 | 区分环境温度与介质温度，泵壳内壁就是介质温度 |
| 载荷 | 内压（工作压力 + 水锤峰值）+ 装配应力（螺栓预紧）+ 管路应力 + 泵脉动 | 承压按长期静液压判，装配应力按 ESC 判，两笔账分开算 |
| 介质 | 清水、盐水 / 海水、稀酸、碱液与洗涤剂、矿物油、有机溶剂、含氯消毒剂 | 按实际接触介质逐项列，浓度 / 温度 / 时间齐全 |
| 寿命 | 与设备同寿命；水处理与通用工业泵常见按 10 年级设计 | 判据是长期外推，不是初始强度 |
| 外观 | 非外观件为主，真正卡的是密封面与法兰面精度 | 收缩率 0.5-0.8%（玻纤增强 PP 公开口径），且看各向异性 |
| 合规 | 部分涉食品 / 医药接触（GB 4806.7-2023 口径）；部分场合要阻燃 | 按件企清单逐项核对，别等整机认证才发现 |
三、材料路线分工：玻纤、矿物、均聚PPH、PVDF、金属泵体各管一段
结论先说：这几条路线不是替代关系，是分工关系——玻纤增强 PP 强在刚度、耐蠕变与尺寸稳定，矿物填充 PP 强在尺寸与耐介质一致性，均聚 PPH、PVDF 与金属强在温度上限与承压等级。
| 路线 | 拿到什么 | 代价 | 适合哪一段 |
|---|
| 玻纤增强改性 PP | 刚度与耐蠕变提升，收缩率可压到 0.5-0.8%（公开口径：模量 4000-5500 MPa、拉伸 80-95 MPa、HDT 145-150℃） | 各向异性；玻纤与基体界面在长期介质下可能成为渗透通道；耐冲蚀一般 | 中小型泵体、阀壳、法兰刚度要求高的位置 |
| 矿物填充改性 PP | 收缩与耐介质更一致，成本可控（公开口径：20% 矿物体系模量约 2700 MPa、HDT(0.45MPa) 约 108℃、收缩率约 0.88%） | 刚性、耐蠕变不如玻纤体系 | 常压 / 低压阀壳、洗涤剂与弱碱工况、法兰尺寸件 |
| 均聚 PP（高分子量、低 MFR） | 化学稳定性与耐蠕变更好，承压管材走的就是这条路（公开口径：MFR 低至 0.25 g/10min、OIT ≥60 min） | 脆、抗冲差，复杂结构成型窗口窄 | 简单回转体、承压管件 |
| PVDF / 氟塑料 | 耐化学等级与耐温上限更高，抗渗透好 | 成本高、加工窗口窄、刚性需结构补 | 强溶剂、强氧化性介质；高温承压 |
| 金属泵体（含衬里） | 承压等级、耐冲蚀、尺寸精度天然够 | 重、需防腐或衬里、成型自由低 | 高扬程大流量、高含固介质、机械密封精度位 |
清水常温低扬程，两条 PP 路线都够用，按法兰刚度决定加不加玻纤；洗涤剂与弱碱工况，矿物填充更稳；长期承压的回转结构参考管材的低 MFR 均聚路线，复杂泵壳这个结构不占优。
四、★ 选型判据表：九项判据，每项都带验证方法与标准号
结论先说：这张表最该看第三列——卡住你的通常不是"看哪个指标"，是"拿什么测、测到多少算过"。
| 指标 | 门限值（典型） | 验证方法 · 标准号 | 常见失效 | 通行解法 |
|---|
| 耐液体化学试剂（加载态） | 拉伸强度保留率 ≥85% | GB/T 11547-2008 / ASTM D543 浸泡框架，试样先加载再浸泡 | 长期介质中强度塌 | 耐介质体系 + 基材复核 |
| 断裂伸长率保留率 | 按件企规范，重点看是否断崖式下降 | 同体系浸泡后按 GB/T 1040 测 | 脆化先于强度下降暴露 | 抗氧体系 + 增韧配平 |
| 质量 / 尺寸变化率 | 质量 ±2% 内且趋于稳定；尺寸 ≤1%，密封面 ≤0.5% | GB/T 11547 浸泡前后称重与量尺寸 | 吸液析出；密封面变形即渗漏 | 助剂耐抽出 + 低收缩 |
| 外观（开裂 / 发白 / 发粘 / 变色） | 无开裂、不发粘、无明显粉化 | GB/T 11547 目视，可配显微 | 开裂先出现在应力集中处 | 耐应力开裂体系 + 圆角 |
| 长期静液压强度 | 多温度外推至设计寿命，不以常温单点定 | ISO 1167 / GB/T 6111-2018 本体试验；ISO 9080 / GB/T 18252-2020 外推 | 高温段蠕变衰减，早期开裂 | 低 MFR 高分子量基材 + 稳定抗氧体系 |
| 抗蠕变 / 法兰松弛 | 恒载下法兰间隙与预紧力保持率按件企规范 | 恒温恒载蠕变与应力松弛试验 | 法兰面松弛渗漏（本件最典型失效） | 玻纤增强 + 法兰结构加强 |
| 密封面尺寸精度 | 按件图平面度与密封槽公差 | GB/T 17037.4 / ISO 294-4；整机试压兜底 | 装配渗漏 | 控各向异性 + 后收缩稳定 |
| 耐温 | HDT 按件企；HDT 只作短时判据 | GB/T 1634.2 | 把 HDT 当长期使用温度用 | 长期温度按介质与寿命另核算 |
| 抗氧化 / 阻燃 / 卫生级 | OIT ≥15 min（管材件公开口径）；阻燃与食品接触按件企与 GB 4806.7-2023 | GB/T 19466；GB/T 5169.16 / UL 94 | 氧化性介质消耗抗氧剂；合规不达标 | 抗萃取抗氧体系；无卤阻燃 / 食品接触级配方 |
文字版结论：九行里 加载态耐化学、长期静液压、法兰松弛是主角——前两行决定"能不能选改性 PP"，第三行决定"选上了会不会一年后渗漏"。耐温那行要记住：HDT 是短时受载变形起点，回答不了长期问题。
五、耐化学腐蚀怎么判：介质清单决定一切，"短期浸泡没变化"不等于耐腐蚀
结论先说：耐化学不能笼统说"耐腐蚀"，必须按实际接触介质逐项列；每一项还要带浓度、温度、时间三个条件，缺一个，结论都不可用。
| 介质类型 | 对材料的主要作用 | 判据落点 |
|---|
| 清水 / 热水 | 水解 + 热氧老化，温度越高越快 | 力学保留率 + OIT |
| 盐水 / 海水 | 渗透 + 电化学环境（影响填料与助剂） | 盐水浸泡 + 尺寸 |
| 稀酸 | 对 PP 本体影响有限，对玻纤界面影响大 | 界面与力学保留率 |
| 碱液 / 洗涤剂 | 表面活性剂 + 应力协同诱发 ESC | 加载状态下的 ESC 评价 |
| 矿物油 | 助剂被萃取迁移，表面发黏发白 | 质量变化率 + 外观 |
| 有机溶剂（芳烃、卤代烃） | 溶胀甚至溶解，非极性 PP 对芳烃敏感 | 质量与尺寸变化率（常直接否决） |
| 含氯 / 过氧化物消毒剂 | 氧化性介质持续消耗抗氧剂 | OIT + 长期浸泡后的分子量级评价 |
三要素必须齐全：浓度、温度、时间任一项差一个量级，结论就可能反过来。"耐酸碱"三个字在选型里没有信息量。
敢否定一个常见做法：把"短期浸泡没有变化"当成耐化学合格。
>
这是错的，在泵阀件上错得最贵。PP 的化学侵蚀很多是慢性的：介质先渗透进表层、降低玻璃化转变温度、诱发银纹，在应力协同下扩展成裂纹——件在几周或几个月后才裂，而第一批浸泡试样早就"合格"出报告了。
>
正确做法只有一条：耐化学验证必须在加载状态下做。 受应力的试样和无应力试样，结果差一个量级。
加载浸泡三条路：恒应变法（弯曲加载、应变 1.0-2.0%、介质中 50-80℃，ISO 6252）；恒拉伸应力法（恒应力浸入实际介质如洗涤剂、40℃，ISO 22088-3）；弯条法（10% Igepal CO-630、50±0.5℃ 记 F₅₀，ASTM D1693）。每组都要同时放一组无应力试样并排报。
氧化性介质还要看机理：公开资料（A 级，*Polymers* 2019）显示，含游离氯 2-5 mg/L 的水中，α 晶 PP-R 抗氧剂约 250 h 耗尽、β 晶 PP-R 约 1250 h；60℃ 氯水 1500 h 后重均分子量由 742 降至 45 kg/mol。
六、耐水压与长期静液压怎么判：常温能过，不代表 60-80℃ 能过
结论先说：承压有两本账——瞬时压力（含水锤）和长期静压，判据完全不同；长期静压的门限随温度急剧下降。
| 判据 | 验证方法与标准号 | 常见失效 | 通行解法 |
|---|
| 瞬时压力 / 爆破（水锤峰值、超压） | 短时保压与爆破按件企规范；管道系统试压口径可参照 ≥1.5 倍工作压力保压 30 min 无压降（GB/T 18742.3-2017 体系） | 瞬时开裂、法兰崩边 | 结构加强 + 法兰与圆角设计 |
| 短期静液压（常温泵体常规承压） | ISO 1167 / GB/T 6111-2018 静液压本体试验 | 厚壁处蠕变变形 | 基材档位 + 壁厚 |
| 长期静液压（设计寿命内持续承压） | ISO 9080 / GB/T 18252-2020：取 20℃、60-70℃、95℃ 等级温度，失效时间分 10-100 h、100-1000 h、1000-8760 h、>8760 h 四区间外推；≥97.5% 数据点须位于参考曲线上方 | 高温段门限衰减，早期开裂 | 稳定抗氧体系 + 低 MFR 高分子量基材 + 玻纤提耐蠕变 |
| 玻纤增强件附加项 | 浸泡 + 静液压组合验证 | 界面成为渗透通道 | 界面处理 + 配比与耐介质体系一起定 |
温度这一项最贵：长期静液压强度是随温度往下走的斜线，常温能过的压力值到 60-80℃ 可能只剩一半。
敢否定一个常见做法：拿常温静液压数据去定承压件的承压等级。
>
样品常温压住了，报告漂亮，件上到 70℃ 热水工况跑半年开始裂。长期承压件的判据不是单点压力值，是多温度外推出来的寿命曲线。
玻纤增强是双刃的：提刚度与耐蠕变有利，但界面在长期介质下可能成为渗透的快速通道，所以必须做"浸泡 + 静液压"组合验证。
七、常见失效与根因：四个现象，四条根因
结论先说：这四条里真正属于"料不行"的很少，多数是"验证条件做少了"和"该改结构的地方改了配方"。
失效一：法兰面松弛渗漏——本件最典型的失效。 螺栓一直压着，材料在温度和介质协同下慢慢让位，预紧力掉下来，介质从密封面挤出。先查法兰刚度与蠕变，再查密封圈。
失效二：长期介质中界面失效、表面鼓包发白。 玻纤增强件特有：介质沿纤维 / 基体界面渗透，界面脱粘后强度断崖式下降。这在纯基体体系里不明显，在玻纤体系里必须单独验。
失效三：装配后渗漏，件尺寸却在公差内。 不是"料缩了"，是收缩各向异性 + 后收缩，法兰面表现为局部不平。这是换料的连带成本，不是料的缺陷。
失效四（敢否定）：介质含颗粒导致流道冲蚀，就提高玻纤含量。 这是错的。玻纤提高的是刚度与耐蠕变，对冲蚀速率帮助有限，而加量上去、抗冲与界面耐介质性一起下降，等于用一个新问题换一个旧问题。 冲蚀要处理流速与冲刷角度、表面状态、介质含固率三件事。
八、验证顺序：先加载浸泡，最后才是长期运行
结论先说：顺序错了，成本会在最后一步集中爆出来；第一级加载浸泡不过，后面所有验证都是浪费。
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① 介质相容性筛选（加载状态下浸泡）
实际介质 + 浓度 + 温度 + 时间；应力组与无应力组并排
↓ 五项变化判据任一项超门限、或应力组先开裂 → 退回基材与体系，别动模具
② 常温压力与爆破
ISO 1167 / GB/T 6111-2018 本体试验；整机试压 ≥1.5 倍工作压力保压 30 min
↓ 不过 → 退回壁厚与法兰结构
③ 不同温度的长期静液压外推
20℃ / 60-70℃ / 95℃ 取点，按 ISO 9080 / GB/T 18252-2020 外推至设计寿命
↓ 外推曲线在设计点上不够 → 直接换路线，不要再调配方
④ 蠕变与法兰松弛
恒温恒载下法兰间隙与预紧力保持率，重点看升温后表现
↓ 不过 → 退回玻纤配比与法兰结构
⑤ 装配密封与整机试压
密封面尺寸、装配扭矩、通水试压、螺栓预紧复测
↓ 不过 → 退回模具收缩率与密封结构
⑥ 长期运行验证
实际介质、实际温度，连续或按工况循环运行
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最常见的错误是跳过 ① 和 ③，直接用试模件做常温试压：试模件成型条件是临时的，数据没有代表性；常温试压只回答"现在压得住"，回答不了三年后。
一个内行细节：加载浸泡试样要从真实安装位置取向取样；浸泡后先按标准状态调节再测，表面残留介质不擦净，数值会虚高或虚低。
九、反向诚实：这几种情况，泵体阀门壳体不该用改性PP
结论先说：长期 90℃ 以上、强溶剂或强氧化性介质、高扬程大流量，这三类里出现任何一类，改性 PP 就不该当首选；出现两类，基本可以直接排除。
| 出现的情况 | 为什么改性PP不合适 | 该往哪走 |
|---|
| 长期使用温度 ≥90℃（尤其热水、蒸汽侧） | 长期耐热受抗氧体系寿命限制；温度上去，长期静液压门限急剧下降 | 均聚 PPH（高分子量、低 MFR）、PVDF，或金属泵体 + 衬里 |
| 强溶剂（芳烃、卤代烃）或强氧化性介质 | 非极性 PP 对芳烃溶胀敏感；氧化性介质持续消耗抗氧剂 | 氟塑料衬里、PVDF、PTFE、陶瓷 |
| 高扬程、大流量（承压等级高、水锤冲击大） | 长期承压靠外推，承压等级越高，外推不确定度越大 | 金属泵体（铸件 / 不锈钢）+ 内衬，或陶瓷泵 |
| 介质含高硬度固相颗粒且流速高 | 表面硬度与耐冲蚀有限，冲蚀速率由介质与流速主导 | 耐磨衬里、陶瓷、金属 |
| 要求金属级密封面精度（高压机械密封位） | 收缩、后收缩与蠕变与金属差一个量级 | 金属件，或金属 + 塑料复合结构 |
只要"长期高温"和"强腐蚀性介质"同时出现，或承压等级超出外推可信区间，这个件就不该用改性 PP 硬撑。 遇到这类需求，先把话讲清楚，再谈有没有折中的结构方案——硬接下来，最后都要用返工和索赔还回去。
十、换料风险清单：从金属泵体换到改性PP要先确认的七件事
结论先说：客户真正担心的不是性能，是"我现在的模具、机台和密封结构要不要改"。
| 要动的项 | 需要确认什么 | 不做会怎样 |
|---|
| 模具收缩率 | 玻纤 / 矿物体系与原方案差多少；各向异性要单独确认 | 法兰面不平、密封槽超差 |
| 后收缩 | 件放置后的尺寸漂移 | 装机合格、放一阵后渗漏 |
| 浇口与排气 | 玻纤体系熔接线位置变化；法兰环向熔接线是薄弱位 | 熔接线处开裂 |
| 料温与模温 | 玻纤体系模温影响浮纤与取向 | 表面缺陷、方向性差 |
| 干燥 / 保压脱模 | 按具体体系定，不可照搬原工艺；收缩差异带来变形与顶白 | 银丝气泡；变形、平面度超差 |
| 密封结构 | 塑料件刚度低于金属，密封形式与螺栓预紧要重新核算 | 预紧力不足、松弛渗漏 |
| 验证顺序 | 加载浸泡 → 常温试压 → 多温度外推 → 蠕变松弛 → 整机试压 | 风险全压到最后一步爆发 |
十一、一页纸汇报对照表：五类泵阀场景直接上报
结论先说：判断这张表是否合格只有一条——客户拿它，能不能在一次会上把材料方向定下来。
| 场景 | 推荐路线 | 关键指标 | 验证标准 | 需先确认的条件 |
|---|
| 常温清水循环泵体（低扬程） | 玻纤增强改性 PP（GF20-30）或矿物填充 PP | 加载浸泡后力学保留率、密封面尺寸 | GB/T 11547 + GB/T 6111 | 介质清单、最高水温 |
| 洗涤剂、弱碱、60-70℃ 清洗泵 | 矿物填充 PP（20% 矿物级耐碱口径） | 耐碱 + 耐热水浸泡、加载 ESC | GB/T 11547 + ASTM D1693 | 洗涤剂浓度、装配应力 |
| 盐水 / 海水工况 | 玻纤或矿物填充改性 PP | 盐水浸泡后尺寸与外观 | GB/T 11547 + GB/T 16422.2 | 游离氯浓度、含固颗粒 |
| 长期 90℃ 以上或强溶剂 / 强氧化介质 | 改性 PP 不优先：均聚 PPH / PVDF / 金属 + 衬里 | 长期静液压外推、耐化学等级 | GB/T 18252 / ISO 9080 | 温度、介质浓度、设计寿命 |
| 高扬程、大流量（承压等级高） | 改性 PP 不优先：铸件 / 不锈钢 + 衬里、陶瓷泵 | 设计压力、长期静液压 | GB/T 6111 / ISO 1167 | 设计压力、水锤条件 |
文字版结论：同一个泵房里，一台走改性 PP 壳体、一台走金属衬里，是完全正常的配置。每个位置对上它自己的介质与承压等级就够了。
十二、泵阀件上最容易出问题的，往往不是料
泵体与阀门壳体在公开资料里讨论最集中的三类问题是：长期高温介质浸泡后的强度衰减、介质与装配应力协同下的环境应力开裂、法兰与密封面的松弛渗漏。 三类问题指向同一个判断——这类件的验证必须"加载 + 带介质 + 长期"三件事同时做到。
通行做法是把三件事一起定：基材档位、增强方式（玻纤提耐蠕变或矿物稳尺寸）、稳定体系（抗氧 + 耐介质助剂）；法兰这类长期受压面还要在结构上给刚度。行业里最常见的偏差，是只做无应力版本的浸泡。
宁波市科隆新材料有限公司在这类件上常供的是自产改性聚丙烯（PP）造粒里的玻纤增强与矿物填充方向，按介质清单、介质温度与承压等级给到对应的基材档位、增强方式与稳定体系，重点解决"浸泡后强度衰减、介质与应力协同开裂、法兰面松弛渗漏"这三件事；配方按件调，可配合做加载浸泡小样比对、多温度静液压取点与试模验证。
常见问答
问：耐化学报告是浸泡 168 小时合格的，能不能用？
答：看两件事：试样有没有加载（无应力浸泡参考价值很低）、介质条件与实际工况差多少（浓度、温度、时间任一项差一个量级，结论可能反过来）。
问：泵壳压力不高，是不是可以不用玻纤？
答：法兰面长期受压又有温度，矿物填充就够用且尺寸更稳；法兰刚度不够、装配后会翘，就上玻纤增强——但玻纤件要补做"浸泡 + 静液压"组合验证。
问：含氯消毒水能不能用？
答：含游离氯 2-5 mg/L 时抗氧剂会被持续消耗，α 晶体系约 250 h 耗尽、β 晶体系约 1250 h。含氯工况下抗氧体系比增韧体系更值得投入。
十三、最后说三句
第一，耐化学不是"泡不坏"，是"应力和介质同时在场时能活多久"。 短期浸泡没变化不等于耐腐蚀。
第二，承压是三本账：瞬时压力、常温短期静压、多温度长期外推。 设计寿命的结论只能来自第三本账。
第三，验证顺序比验证项更贵：加载浸泡 → 常温试压 → 多温度外推 → 蠕变松弛 → 整机试压。
下一篇讲工业脚轮与滚轮——那个件最怕的不是承重，是滚动磨耗和包胶界面。
关于我们
关于我们，四句话：
一、改性聚丙烯：均聚 / 无规共聚 / 抗冲共聚；
二、改性方向：填充、玻纤增强、增韧、阻燃、低气味低 VOC、耐候、免喷涂耐划伤；
三、各大石化厂 PP 树脂贸易；
四、副牌料、大包料现货。
宁波市科隆新材料有限公司，自产改性聚丙烯（PP）造粒，覆盖均聚 / 无规共聚 / 抗冲共聚三档基材，以及填充、玻纤增强、增韧、阻燃、低气味低 VOC、耐候、免喷涂耐划伤等改性方向；兼营各大石化厂 PP 树脂、副牌料与大包料。
The pump body and valve housing are made of modified PP. The material needs to be immersed in the medium for a long time and also withstand long-term pressure — 'just being able to endure' is not enough. This article discusses how to list the media, the criteria for chemical resistance under loading conditions, multi-temperature extrapolation for long-term hydrostatic pressure, flange creep relaxation and verification order, and explains why modified PP should not be forced in long-term scenarios above 90°C, with strong solvents, or in high-head situations.
There was an engineer who makes chemical metering pumps, and he brought a cracked pump casing to ask: 'I've used it for four months, and it cracked from the base of the flange, breaking as soon as I applied force. The material's tensile strength was tested and is up to standard. Could there be a problem with the material?'
I asked three questions: What is the medium, what temperature, and how much pressure. He answered: tap water with a little descaler, sixty to seventy degrees, pressure not high.
The direction has been determined—it's not that the 'strength is insufficient,' but that 'being in the medium for a long time and constantly pulled by the flange bolts' caused it to crack at the circle with the greatest stress.
For parts like pump bodies and valve housings, the material needs to be able to exist long-term in the medium and under long-term pressure. It must 'live' under the simultaneous presence of these two conditions, not just 'endure' them.
"Withstand" means it doesn't deform after a short soak; "survive" means that after thousands of hours, the flange is still there, the sealing surface is still intact, and the bolt preload is still maintained. The methods of verification for these two things are completely different.
1. Failure site of pump and valve parts: the crack is not in the flow passage, but on the circle with the maximum stress
Conclusion first: The most common failure of this type of part is not bursting under pressure, but cracking from the base of the flange, around the screw holes, and at the fillets — the locations almost all point to a combination of 'medium and stress'.
Scene 1: Cracking at the base of the flange, material inspection passed. The part was used for a few months and cracked radially from the fillet of the flange. Conventional physical testing could not detect any issues—this is environmental stress cracking: the medium penetrates and induces crazing, and assembly stress and preload forces pull it open. Short-term soaking does not reveal it because it is not under load.
A detail for insiders: For the same material and the same medium, a stress-free sample may show no change after soaking for 1000 hours; however, after being loaded to 1% strain, silver streaks can appear in a few hundred hours. Reports that only conduct stress-free soaking are basically of no reference value for pressure-bearing components.
2. Six-Dimensional Breakdown of Working Conditions: Temperature, Internal Pressure, Medium, Lifespan, report the numbers first
Conclusion first: In six dimensions, the medium and temperature are veto lines; the load dimension should be split into 'internal pressure' and 'assembly stress' as two separate accounts.
| Dimension | Actual operating conditions | Requirements for the materials |
|---|
| Temperature | Normal temperature circulating water 20-40°C; hot water and cleaning conditions 60-80°C, locally can reach above 90°C | Distinguish between ambient temperature and medium temperature; the inner wall of the pump casing is the medium temperature. |
| Load | Internal pressure (operating pressure, water hammer peak) Assembly stress (bolt preloading) Pipeline stress Pump pulsation | Pressure-bearing is judged according to long-term static hydraulic pressure, assembly stress is judged according to ESC, and the two accounts are calculated separately. |
| Medium | Fresh water, salt water / seawater, dilute acid, alkaline solution and detergents, mineral oil, organic solvents, chlorine-containing disinfectants | List each item according to the actual contact medium, with complete concentration/temperature/time information |
| Lifespan | The same lifespan as the equipment; water treatment and general industrial pumps are commonly designed according to a 10-year grade. | The criterion is long-term extrapolation, not initial strength. |
| Appearance | Mainly not exterior parts; the real bottleneck is the accuracy of the sealing surface and the flange surface. | Shrinkage rate 0.5-0.8% (glass fiber reinforced PP, open mold), and consider anisotropy |
| Compliance | Some parts involve food/medicine contact (GB 4806.7-2023 caliber); some occasions require flame retardancy | Check the items on the component list one by one; don't wait until the whole machine is certified to find out. |
3. Division of material routes: each pipe section is assigned to glass fiber, mineral, homopolymer PPH, PVDF, and metal pump body respectively.
Conclusion first: These few routes are not alternatives to each other, but complementary in function—glass fiber reinforced PP is strong in stiffness, creep resistance, and dimensional stability; mineral-filled PP is strong in dimensional and medium resistance consistency; homo PPH, PVDF, and metals are strong in temperature limits and pressure ratings.
| Route | Get what | Cost | Suitable for which section |
|---|
| Glass fiber reinforced modified PP | Stiffness and creep resistance improved, shrinkage rate can be reduced to 0.5-0.8% (public specifications: modulus 4000-5500 MPa, tensile strength 80-95 MPa, HDT 145-150°C) | Anisotropic; the glass fiber and matrix interface may become a permeation channel under long-term medium exposure; generally erosion-resistant | Positions on small and medium-sized pump bodies, valve bodies, and flanges that require high stiffness |
| Mineral-filled modified PP | Shrinkage and medium resistance are more consistent, and costs are controllable (public data: 20% mineral system modulus about 2700 MPa, HDT(0.45MPa) about 108°C, shrinkage rate about 0.88%) | Rigidity and creep resistance are not as good as the glass fiber system | Atmospheric / low-pressure valve bodies, detergents and mild alkali conditions, flange dimension parts |
| Homopolymer PP (high molecular weight, low MFR) | Better chemical stability and creep resistance—pressurized pipes follow this path (public specifications: MFR as low as 0.25 g/10min, OIT ≥60 min) | Brittle, impact-resistant, narrow forming window for complex structures | Simple rotating body, pressure-bearing pipe fittings |
| PVDF / Fluoroplastics | Higher chemical resistance and higher maximum temperature limit, good impermeability | High cost, narrow processing window, rigidity requires structural reinforcement | Strong solvents, strongly oxidizing media; high temperature and pressure |
| Metal pump body (including lining) | Pressure rating, erosion resistance, and dimensional accuracy are naturally sufficient | Heavy, requires corrosion resistance or lining, low forming freedom | High lift and large flow, high solid content medium, mechanical seal precision position |
For clear water at normal temperature with low lift, both PP routes are sufficient; whether to add fiberglass depends on the flange stiffness. For detergent and weak alkaline conditions, mineral-filled is more stable. For long-term pressurized rotating structures, refer to the low MFR homopolymer route of the pipe material; this structure is not advantageous for complex pump casings.
4. ★ Selection Criteria Table: Nine criteria, each with validation methods and standard numbers
Conclusion first: The column you should pay the most attention to in this table is the third one — what usually trips you up is not 'which indicator to look at,' but 'what to measure with and how much counts as passing.'
| Indicator | Threshold Value (Typical) | Verification Method · Standard Number | Common Failures | Common solution |
|---|
| Resistant to liquid chemical reagents (loaded state) | Tensile strength retention ≥85% | GB/T 11547-2008 / ASTM D543 Soaking frame, samples are loaded first and then soaked | Long-term medium strength collapse | Medium-resistant system Substrate review |
| Retention rate of elongation at break | According to itemized specifications, the focus is on whether there is a cliff-like decline | After immersion in the same system, test according to GB/T 1040 | Embrittlement occurs before strength degradation exposure | Antioxidant System Toughening Balance |
| Mass / Dimensional Variation Rate | Mass ±2% and tending to be stable; dimensions ≤1%, sealing surface ≤0.5% | GB/T 11547 Weighing and Measuring Dimensions Before and After Soaking | Liquid absorption and precipitation; leakage due to deformation of the sealing surface | Additive leach resistance Low shrinkage |
| Appearance (cracking / whitening / becoming sticky / discoloration) | No cracking, not sticky, no obvious chalking | GB/T 11547 Visual inspection, can be equipped with a microscope | Cracks first appear at points of stress concentration | Stress cracking resistant system Fillet |
| Long-term static liquid pressure strength | Extrapolated from multiple temperatures to the design life, not determined by a single point at room temperature | ISO 1167 / GB/T 6111-2018 Body Testing; ISO 9080 / GB/T 18252-2020 Extrapolation | Creep degradation at high temperature section, early cracking | Low MFR high molecular weight substrate, stable anti-oxidation system |
| Creep Resistance / Flange Relaxation | Flange clearance and pre-tightening force retention rate under constant load shall follow the enterprise standard | Constant Temperature and Constant Load Creep and Stress Relaxation Test | Flange face relaxation leakage (the most typical failure in this case) | Glass fiber reinforced flange structure reinforcement |
| Sealing surface dimensional accuracy | Flatness of each part drawing and tolerance of sealing groove | GB/T 17037.4 / ISO 294-4; final pressure test of the whole machine | Assembly leakage | Control anisotropy Stabilize post-shrinkage |
| Temperature resistant | HDT by piece plan; HDT only used as a short-term criterion | GB/T 1634.2 | Use HDT as the long-term operating temperature | Long-term temperature is calculated separately according to the medium and lifespan |
| Antioxidant / Flame Retardant / Hygienic Grade | OIT ≥15 min (for the open diameter of pipes and components); flame retardant and food contact according to GB 4806.7-2023 | GB/T 19466; GB/T 5169.16 / UL 94 | Oxidizing media consume antioxidants; compliance does not meet the standard | Anti-extraction and anti-oxidation system; halogen-free flame retardant / food contact grade formulation |
Text version conclusion: In the nine rows, chemical resistance, long-term static hydrostatic pressure, and flange relaxation are the main factors—the first two rows determine 'whether to choose modified PP,' and the third row determines 'if chosen, whether it will leak after a year.' For the temperature resistance row, remember: HDT is the onset of deformation under short-term load and cannot answer long-term questions.
5. How to determine chemical corrosion resistance: the list of media determines everything; 'no change after short-term soaking' does not mean corrosion resistance.
Conclusion first: Chemical resistance cannot be generally described as 'corrosion-resistant'; it must be listed item by item according to the actual contact media. Each item must also include three conditions: concentration, temperature, and time. Missing any one of these, the conclusion is not usable.
| Medium type | The main function of the material | Criterion landing point |
|---|
| Cold Water / Hot Water | Hydrolysis Thermal-oxidative aging, the higher the temperature, the faster it occurs | Mechanical Retention Rate OIT |
| Saltwater / Seawater | Permeation Electrochemical environment (affects fillers and additives) | Brine soaking Size |
| dilute acid | Limited effect on PP itself, significant effect on the glass fiber interface | Interface and Mechanical Retention Rate |
| Alkaline solution / Detergent | Surfactant Stress Co-activation Induced ESC | ESC evaluation under loading conditions |
| Mineral oil | The additives are extracted and migrated, causing the surface to become sticky and whitish. | Rate of Quality Change Appearance |
| Organic solvents (aromatic hydrocarbons, halogenated hydrocarbons) | Swelling or even dissolving, nonpolar PP is sensitive to aromatics | Quality and dimensional variation rate (often directly rejected) |
| Chlorine / Peroxide Disinfectant | Oxidizing medium continuously consumes antioxidants | OIT Molecular Weight Evaluation After Long-Term Soaking |
All three elements must be complete: concentration, temperature, and time; if any one of them is off by an order of magnitude, the conclusion may be reversed. The three words 'acid and alkali resistance' carry no information in selection.
Can one deny a common practice: treating 'no change after short-term soaking' as chemically resistant pass.
>
This is wrong, and mistakes are the most costly on pump and valve components. Many of PP's chemical attacks are chronic: the medium first penetrates the surface layer, lowers the glass transition temperature, induces crazing, and under the synergy of stress, expands into cracks—the component only cracks after a few weeks or months, while the first batch of soaked samples had long 'passed' and reports were issued.
>
There is only one correct approach: chemical resistance testing must be done under load. The results differ by an order of magnitude between stressed and unstressed samples.
Three soaking loading methods: Constant strain method (bending load, strain 1.0-2.0%, in medium at 50-80℃, ISO 6252); Constant tensile stress method (constant stress immersed in actual medium such as detergent, 40℃, ISO 22088-3); Bent strip method (10% Igepal CO-630, 50±0.5℃, record F₅₀, ASTM D1693). For each group, a set of unstressed samples should be placed and reported alongside.
The oxidative medium also depends on the mechanism: According to publicly available data (A level, *Polymers* 2019), in water containing 2-5 mg/L of free chlorine, the antioxidant in α-crystal PP-R is depleted in about 250 hours, while in β-crystal PP-R it is about 1250 hours; after 1500 hours in 60°C chlorinated water, the weight-average molecular weight decreases from 742 to 45 kg/mol.
6. How to judge water pressure resistance and long-term static hydrostatic pressure: passing at room temperature does not mean it can pass at 60-80℃.
Conclusion first: There are two kinds of pressure to consider — instantaneous pressure (including water hammer) and long-term static pressure, with completely different criteria; the threshold for long-term static pressure drops sharply with temperature.
| Criterion | Verification Method and Standard Number | Common Failures | Common solution |
|---|
| Instantaneous Pressure / Surge (Water Hammer Peak, Overpressure) | Short-term pressure holding and bursting should be carried out according to component specifications; the test pressure of the pipeline system can refer to maintaining a pressure of ≥1.5 times the working pressure for 30 minutes without pressure drop (GB/T 18742.3-2017 system). | Instantaneous cracking, flange chipping | Structural Reinforcement Flange and Fillet Design |
| Short-term static hydraulic (normal pressure-bearing of pump body at room temperature) | ISO 1167 / GB/T 6111-2018 Hydrostatic Body Test | Creep deformation in thick-walled areas | Base Material Grade Wall Thickness |
| Long-term static hydraulic pressure (continuously under pressure within the design life) | ISO 9080 / GB/T 18252-2020: Take grade temperatures of 20℃, 60-70℃, 95℃, and extrapolate failure times in four intervals of 10-100 h, 100-1000 h, 1000-8760 h, >8760 h; ≥97.5% of the data points must be above the reference curve | High-temperature stage threshold attenuation, early cracking | Stable antioxidant system, low MFR high molecular weight base material, glass fiber to improve creep resistance |
| Additional Items for Glass Fiber Reinforced Components | Soaking Static and Hydraulic Combination Verification | The interface becomes a penetration channel | Interface processing is determined together with the ratio and the medium-resistant system |
Temperature is the most expensive factor: long-term hydrostatic strength decreases with temperature in a downward slope, and the pressure value that can be passed at room temperature may be reduced by half at 60-80°C.
Dare to deny a common practice: using ambient temperature static hydraulic data to determine the pressure rating of a pressure-bearing component.
>
The sample was pressed at room temperature, the report looks good, but it started to crack after running under 70°C hot water conditions for half a year. The criterion for long-term pressure-bearing parts is not a single pressure value, but a lifespan curve extrapolated from multiple temperatures.
Glass fiber reinforcement is a double-edged sword: it helps increase stiffness and creep resistance, but the interface may become a fast channel for permeation under long-term exposure to media, so a combined 'soaking + static hydraulic' verification must be performed.
7. Common Failures and Root Causes: Four Phenomena, Four Root Causes
Conclusion first: Among these four cases, very few truly fall under 'the material won't work'; most are 'insufficient testing of conditions' and 'places where the structure should have been changed, the formula was changed instead'.
Failure 1: Flange surface relaxation leakage — This is the most typical failure of this component. The bolts remain tightened, but the material slowly yields under the combined effects of temperature and medium, the preload decreases, and the medium is squeezed out from the sealing surface. First, check the flange stiffness and creep, then check the sealing ring.
Failure 2: Long-term interface failure in the medium, with surface blistering and whitening. Specific to fiberglass-reinforced parts: the medium penetrates along the fiber/matrix interface, and after interfacial debonding, the strength drops sharply. This is not obvious in pure matrix systems, but in fiberglass systems it must be tested separately.
Failure Three: Leakage after assembly, yet the part dimensions are within tolerance. It's not 'material shrinkage'; it's anisotropic shrinkage with subsequent contraction, causing the flange surface to exhibit local unevenness. This is the collateral cost of changing materials, not a defect of the material.
Invalid Point Four (Dare to Deny): It is said that if the medium contains particles causing flow channel erosion, then increasing the glass fiber content is the solution. This is wrong. Increasing glass fiber improves stiffness and creep resistance, but has limited effect on erosion rate. Moreover, as the amount increases, both impact resistance and interfacial resistance to the medium decrease, essentially replacing one problem with another. To deal with erosion, you need to address three things: flow velocity and impact angle, surface condition, and solid content in the medium.
8. Verification sequence: first load soaking, and finally long-term operation
Conclusion first: if the order is wrong, the costs will all explode at the final step; if the first-level loading soaking fails, all subsequent verifications are a waste.
`
① Medium compatibility screening (soaking under loaded conditions)
Actual medium Concentration Temperature Time; Stress group and no-stress group side by side
↓ If any of the five change criteria exceed the threshold, or if the stress group cracks first → return to the base material and system, do not move the mold
② Normal Temperature Pressure and Explosion
ISO 1167 / GB/T 6111-2018 Body test; complete machine pressure test ≥1.5 times the working pressure, hold for 30 minutes
↓ However → Revert to wall thickness and flange structure
③ Long-term static hydraulic extrapolation at different temperatures
Take samples at 20℃ / 60-70℃ / 95℃, and extrapolate to the design life according to ISO 9080 / GB/T 18252-2020
↓ The extrapolation curve is insufficient at the design point → Directly change the route, do not adjust the formula anymore
④ Creep and Flange Relaxation
Inter-flange gap and preload retention under constant temperature and constant load, focusing on the performance after heating
↓ However → Revert the glass fiber ratio and flange structure
⑤ Assembly Sealing and Complete Machine Pressure Test
Sealing surface dimensions, assembly torque, water pressure test, re-measurement of bolt preload
↓ However → Return mold shrinkage rate and sealing structure
⑥ Long-term operation verification
Actual medium, actual temperature, continuous or cyclic operation according to working conditions
`
The most common mistake is skipping ① and ③, and directly using the trial mold for room temperature pressure testing: the forming conditions of the trial mold are temporary, and the data are not representative; room temperature pressure testing only answers 'whether it can hold pressure now,' and cannot answer about three years later.
An insider detail: When loading soaked samples, they should be taken from their actual installation orientation; after soaking, adjust them to standard conditions before measuring. If the remaining surface medium is not wiped off, the values will be falsely high or low.
9. Reverse Honesty: In these situations, the pump body and valve casing should not use modified PP
Conclusion first: For long-term exposure above 90℃, strong solvents or strong oxidizing media, and high head with large flow—if any one of these three occurs, modified PP should not be the first choice; if two occur, it can basically be ruled out directly.
| The situation that occurred | Why is modified PP not suitable | Which way should I go? |
|---|
| Long-term use temperature ≥90℃ (especially on the hot water and steam side) | Long-term heat resistance is limited by the lifespan of the antioxidant system; as the temperature rises, the long-term static hydraulic threshold drops sharply. | Homopolymer PPH (high molecular weight, low MFR), PVDF, or metal pump body lining |
| Strong solvents (aromatic hydrocarbons, halogenated hydrocarbons) or strong oxidizing media | Non-polar PP is sensitive to swelling from aromatic hydrocarbons; oxidative media continuously consume antioxidants | Fluoroplastic lining, PVDF, PTFE, ceramic |
| High lift, large flow (high pressure rating, strong water hammer impact) | Long-term pressure relies on extrapolation; the higher the pressure level, the greater the extrapolation uncertainty. | Metal pump body (casting / stainless steel) lined, or ceramic pump |
| The medium contains high-hardness solid particles and has a high flow rate | Surface hardness and erosion resistance are limited, and the erosion rate is dominated by the medium and flow rate | Wear-resistant lining, ceramics, metal |
| Requires metal-level sealing surface precision (high-pressure mechanical seal position) | Shrinkage, post-shrinkage, and creep differ from metals by an order of magnitude | Metal parts, or metal-plastic composite structures |
As long as 'long-term high temperatures' and 'highly corrosive media' occur simultaneously, or the pressure rating exceeds the extrapolated reliable range, this part should not rely on modified PP for rigid support. When encountering such requirements, first make the situation clear before discussing whether there is a compromise structural solution — if you proceed rigidly, in the end, it will all have to be returned through rework and claims.
10. Material Change Risk Checklist: Seven Things to Confirm Before Switching from Metal Pump Body to Modified PP
Conclusion first: What customers are really worried about is not performance, but 'whether I need to change my current molds, machines, and sealing structure'.
| Items to move | What needs to be confirmed | What will happen if I don't do it? |
|---|
| Mold shrinkage rate | How different is the fiberglass/mineral system from the original plan; anisotropy needs to be confirmed separately | Flange surface uneven, sealing groove out of tolerance |
| After contraction | Dimensional drift after part placement | Installed correctly, but leaks after being left for a while |
| Gate and Venting | Glass fiber system weld line position changes; the flange circumferential weld line is a weak point | Cracking at the weld line |
| Material Temperature and Mold Temperature | The effect of mold temperature in the fiberglass system on floating fibers and orientation | Surface defects, poor directionality |
| Drying / Pressure-Holding Demolding | It depends on the specific system and cannot copy the original process; shrinkage differences cause deformation and whitening on raised areas. | Silver wire bubbles; deformation, extreme flatness deviations |
| Sealing structure | The rigidity of plastic parts is lower than that of metal, and the sealing method and bolt preload need to be recalculated. | Insufficient preload, loosening and leakage |
| Verification order | Load soaking → Room temperature pressure test → Multi-temperature extrapolation → Creep relaxation → Complete machine pressure test | All the risk is pushed to the final step before it explodes |
Eleven, One-page report comparison table: Direct reporting for five types of pump and valve scenarios
Conclusion first: There is only one criterion to determine whether this table is qualified——whether the client can use it to finalize the direction of the materials in a single meeting.
| Scene | Recommended Route | Key indicators | Verification Standard | Conditions that need to be confirmed first |
|---|
| Normal temperature clear water circulation pump body (low head) | Glass fiber reinforced modified PP (GF20-30) or mineral-filled PP | Mechanical retention rate after soaking, sealing surface dimensions | GB/T 11547 GB/T 6111 | Medium list, maximum water temperature |
| Detergent, weak alkali, 60-70°C cleaning pump | Mineral-filled PP (20% mineral-grade alkali-resistant specification) | Alkali-resistant, resistant to hot water soaking, loaded ESC | GB/T 11547 ASTM D1693 | Detergent concentration, assembly stress |
| Brine / Seawater Conditions | Glass fiber or mineral-filled modified PP | Size and appearance after soaking in saline | GB/T 11547 GB/T 16422.2 | Free chlorine concentration, solid particles content |
| Long-term above 90℃ or strong solvents / strong oxidizing media | Modified PP is not a priority: homopolymer PPH / PVDF / metal lining | Long-term static hydraulic extrusion, chemical resistance grade | GB/T 18252 / ISO 9080 | Temperature, medium concentration, design life |
| High lift, large flow (high pressure rating) | Modified PP not preferred: castings / stainless steel lining, ceramic pumps | Design pressure, long-term static hydraulic pressure | GB/T 6111 / ISO 1167 | Design pressure, water hammer conditions |
Text version conclusion: In the same pump room, it is completely normal to have one pump with a modified PP casing and another with a metal-lined casing. Each position only needs to match its own medium and pressure rating.
12. The parts of pumps and valves that are most prone to problems are often not the material.
The three types of issues most commonly discussed in public materials regarding pump bodies and valve housings are: strength degradation after long-term exposure to high-temperature media, environmental stress cracking under the combined effects of the media and assembly stress, and relaxation leakage of flanges and sealing surfaces. These three types of issues point to the same conclusion — the verification of such components must simultaneously achieve 'loading, media, and long-term' conditions.
The common practice is to determine three things together: the base material grade, the reinforcement method (glass fiber to improve creep resistance or minerals to stabilize dimensions), and the stabilization system (antioxidants and media-resistant additives); for flanges and other surfaces under long-term pressure, stiffness must also be provided in the structure. The most common deviation in the industry is to only do stress-free soaking versions.
Ningbo Cologne New Materials Co., Ltd. commonly supplies its own modified polypropylene (PP) granules for this type of part, focusing on glass fiber reinforcement and mineral filling. Based on the media list, media temperature, and pressure rating, the appropriate grade of base material, reinforcement method, and stabilization system are provided, with emphasis on addressing three issues: 'strength decay after soaking, synergistic cracking from media and stress, and flange surface relaxation leakage.' The formulation is adjusted according to the part and can be tested with small soak-load samples, multi-temperature hydrostatic sampling, and mold trials for verification.
Frequently Asked Questions
Question: The chemical resistance report shows that soaking for 168 hours is qualified. Can it be used?
Answer: It depends on two things: whether the sample was loaded (the reference value for unstressed soaking is very low) and how much the medium conditions differ from the actual working conditions (if the concentration, temperature, or time differs by an order of magnitude, the conclusion may be reversed).
Question: If the pump casing pressure is not high, is it possible to not use fiberglass?
Answer: If the flange surface is under long-term pressure and also exposed to temperature, mineral filling is sufficient and the dimensions are more stable; if the flange stiffness is insufficient and it warps after assembly, then use glass fiber reinforcement—but glass fiber parts need additional "soaking and hydrostatic" combined verification.
Question: Can chlorine disinfectant water be used?
Answer: When free chlorine is 2-5 mg/L, the antioxidant will be continuously consumed. The α crystal system will be depleted in about 250 hours, and the β crystal system in about 1250 hours. Under chlorinated conditions, investing in the antioxidant system is more worthwhile than in the toughening system.
Thirteen, finally say three sentences
First, chemical resistance does not mean 'it won't be damaged by soaking'; it means 'how long it can last when both stress and the medium are present.' Short-term soaking without change does not equal corrosion resistance.
Second, pressure stress involves three accounts: instantaneous pressure, short-term static pressure at normal temperature, and long-term extrapolation at multiple temperatures. Conclusions about the design life can only come from the third account.
Third, the verification sequence is more expensive than the verification items: soak loading → ambient pressure testing → multi-temperature extrapolation → creep relaxation → whole machine pressure testing.
The next article talks about industrial casters and rollers — the thing they fear most is not the load-bearing, but rolling wear and the rubber-covered interface.
About Us
About us, four sentences:
1. Modified polypropylene: homopolymer / random copolymer / impact copolymer;
2. Modification directions: filling, glass fiber reinforcement, toughening, flame retardant, low odor and low VOC, weather resistance, scratch resistance without spraying;
3. Trading of PP resins from major petrochemical plants;
4. Spot goods of secondary brand materials and large-bag materials.
Ningbo Kolong New Materials Co., Ltd. produces modified polypropylene (PP) granules, covering three types of base materials: homopolymer / random copolymer / impact copolymer, as well as modification directions such as filling, glass fiber reinforcement, toughening, flame retardant, low odor and low VOC, weather resistance, and scratch resistance without spraying; also engaged in trading PP resins from major petrochemical plants, secondary brand materials, and large-bag materials.
